Fire Management
and Invasive Plants
A Handbook
U.S. Fish & Wildlife Service
Cover: Prescribed burn to treat salt cedar
(Tamarix spp.). Photo by M. Weisenberger, USFWS.
by Matthew Brooks
U.S. Department of the Interior
U.S. Geological Survey
Western Ecological Research Center
and
Michael Lusk
National Wildlife Refuges
Invasive Species Coordinator
4401 N. Fairfax Dr., Rm. 655B
Arlington, VA 22203
Fire Management
and Invasive Plants
A Handbook
Acknowledgements:
We would like to thank the following people for their
contributions to the publication of this Handbook.
Jenny Ericson for general project oversight.
Karen Murphy, Fred Wetzel, Bill Leenhouts, and
Karen Phillips for their numerous reviews of the
document and resulting edits. Mara Weisenberger
for proofreading and editing the document and
supplying photos. Sue Wilder for gathering
information on fire and invasive species policy.
Karen Miranda Gleason and Kevin Kilbride for
providing background information. Brian McManus,
Chris Pease, Art Latterell and Andy Loranger for
their continued support of the project and help in
moving the project to completion. Aaron Fester for
editing the document to make it more accessible to
the field. Mark Newcastle for layout, format and
design. The compilation and synthesis of information
and the final production of this Handbook was
supported by funding from the U.S. Fish and
Wildlife Service, National Refuge System, Branch of
Fire Management; U.S. Geological Survey, Invasives
and Ecosystems programs; and numerous projects
administered by the Joint Fire Science Program,
most notably project #00-1-2-04.
Suggested citation:
Brooks, M. and M. Lusk. 2008. Fire Management
and Invasive Plants: a Handbook. United States
Fish and Wildlife Service, Arlington Virginia, 27
pp.
Table of Contents
Executive Summary and General Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Section I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Introduction
Section II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Definitions
Section III. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
How Do Plant Invasions Occur?
Section IV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Why Should the Management of Invasive Plants and Fires Be Combined?
Section V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
General Operational Guidelines for Fire Management
Section VI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Specific Operational Guidelines for Major Fire Management Activities
Section VII. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Effectiveness Monitoring
Section VIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Bibliography
Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Laws, Policies And Planning Documents
Guiding the Management of Invasive Plants and Fire
1
Fire management can help maintain natural
habitats, increase forage for wildlife, reduce fuel
loads that might otherwise lead to catastrophic
wildfire, and maintain natural succession. Today,
there is an emerging challenge that fire managers
need to be aware of: invasive plants. Fire
management activities can create ideal opportunities
for invasions by nonnative plants, potentially
undermining the benefits of fire management
actions.
This manual provides practical guidelines that fire
managers should consider with respect to invasive
plants.
What’s the Link Between Fire and Plant Invasion?
The growth and spread of any plant species depends
on two main factors:
1) plant propagule availability: the abundance of
seeds and other plant propagules (i.e., parts of a
plant that can produce a new individual), and
2) plant resource availability: the amount and quality
of resources (sunlight, soil nutrients, etc.) that newly
arrived propagules need to grow.
Postfire conditions can create ideal habitat for
certain plants. When those conditions are created
within easy range of the propagules of invasive
plants, the situation is ripe for an invasion. The
graphs below (Box 1.) illustrate both invasion
potential and subsequent management strategy
based on the relationship between plant propagule
availability and resource availability.
What Can Fire Managers Do?
The best approaches fire managers can take for
reducing the potential for invasive plant infestations
are to minimize or eliminate the introduction of
invasive plant propagules into fire management
areas and minimize the amount of resources
available to any such plants that might find their way
into the burned area.
Primary Guidelines
At a minimum, the following should be applied in all
situations:
Prevent Dispersal of Invasive Plants:
••Locating fire camps and staging areas in areas
relatively free of weeds and other invasive plants.
Plant Propagules
Plant Resources
high
invasion
potential
low
invasion
potential
Invasion Potential
Plant Propagules
Plant Resources
management
response
unnecessary
Management Strategy
reduce
resource
availability
reduce
both
factors
reduce
propagule
pressure
Box 1. Invasion potential and management strategy.
Executive Summary and
General Recommendations
2
••Washing vehicles and equipment before and after
being used within a project area (i.e., treatment
area, fireline).
••Ensuring that any revegetation (i.e., seed mixes)
or other organic material (i.e., straw mulch) that
is introduced into the project area is certified as
weed-free.
Minimize Resources Available to Invasive
Plants:
••Remove only enough vegetation to accomplish
the management objectives (i.e., creating a
managed fuel zone, constructing a fireline).
••As an alternative to vegetation removal, consider
replacing highly flammable vegetation with less
flammable vegetation when creating a managed
fuel zone.
Are Additional Steps Necessary?
The above guidelines should be applied to all
situations. You will need more information––
primarily regarding propagule and resource
availability––to determine if additional preventative
methods are necessary. In these cases, fire
managers need to prioritize which actions will
provide the best results, and these actions can vary
depending on the circumstances associated with
each individual fire. Consult the reference guide
below that includes additional site-based guidelines
providing more specific recommendations associated
with four typical scenarios.
1. Low Propagule Availability
and Low Resource Availability
No major management actions are warranted.
Low propagule availability can occur if survey
data indicate few populations and low densities of
invasive plants.
Low resource availability can occur where
vegetation loss is relatively low and/or recovery
potential is high. Examples include fuels projects
that thin but do not completely remove vegetation
or fires where burn severities are relatively low
and/or native vegetation cover is expected to
reestablish within a few years.
Almost all management actions have the potential
to cause unexpected and undesirable effects (i.e.,
seed mixes or straw mulch can be contaminated
by unwanted species), so they should only be
implemented if there are compelling reasons to
do so.
2. Low Propagule Availability
and High Resource Availability
Management actions should focus on minimizing
resource availability.
In this scenario resource availability is high, such
as following complete removal of vegetation to
create managed fuel zones or after a high severity
fire. If the area has high levels of resource
availability, then it may be most effective to focus
management efforts on reducing these factors.
However, the absence or rarity of invasive plants
may warrant little or no additional management
response.
3. High Propagule Availability
and Low Resource Availability
Management actions should focus on minimizing
propagule availability.
If the area in question is in proximity to large
source populations of invasive plants, then
management of propagule dispersal into the area
may be the best strategy. Focus on preventing the
dispersal of propagules into the project areas, and
on eradicating newly established individuals and
populations at the edges of the invasive plants’
range. Follow-up monitoring is always required to
determine if re-treatment is needed.
4. High Propagule Availability
and High Resource Availability
Management actions are warranted to minimize
both plant propagule availability and resource
availability as discussed above.
3
Using fire as a tool to manage at the landscape scale. Photo by M. Weisenberger, USFWS.
Low Propagule/Low Resource
No major management actions are warranted
where
Vegetation loss from fire is low
Native vegetation is expected to return
quickly
High Propagule/Low Resource
Management actions should focus on
minimizing propagule availability where
Area in question is in proximity to large
source populations of invasive plants.
Low Propagule/High Resource
Management actions should focus on
minimizing resource availability where
Native vegetation is completely removed
but invasive plants are rare or absent from
the area.
High Propagule/High Resource
Management actions are warranted to
minimize both plant propagule availability
and resource availability as discussed above
where
Native vegetation is completely removed
(fuel load management, severe wildfire), and
invasive propagules have access to the area.
Box 2. Summary of Guidelines.
4
The purpose of this manual is to provide practical
guidelines for fire managers to effectively integrate
invasive plant management activities into their
fire management programs. Traditionally, fire
management and invasive plant management
have been conceived and implemented as separate
programs. This manual is designed to help land
managers bridge the gap between these two
disciplines, and in particular give fire managers
the tools they need to integrate invasive plant
management strategies into the fire planning
process. Although this handbook is tailored
specifically for the fire management community
within the National Wildlife Refuge System of the
U.S. Fish and Wildlife Service, it is also relevant
to other agencies and organizations that manage
wildland fire.
Section I
Introduction
U.S. Fish and Wildlife Service fire crew conducting a prescribed burn. USFWS.
5
One of the potentially confusing aspects of invasive
plant management relates to definitions. Many
different terms have been associated with plants
that are land management problems or deemed
undesirable for one reason or another. Because
these terms are often used interchangeably in
management documents, and their usage can be
confusing, some of the most commonly used terms
are defined below. Several commonly used fire
management terms are also described to encourage
consistency across programs.
Accidentally Introduced. Species that dispersed
without intentional human intervention, such as
contaminants of plant stock or planting materials
(i.e., mulches), or by attaching to equipment, shoes,
or animals.
Deliberately Introduced. Species that were
intentionally transported to and cultivated in new
areas for various purposes such as livestock forage,
erosion control, or ornamental horticulture, but
then subsequently spread into areas where they are
unwanted.
Fire Behavior. The rate of spread, residence time,
flame length, and flame depth of an individual fire.
Fire Hazard. Fuel conditions that are deemed
hazardous to human life, property, or valued land
management resources (i.e., natural, cultural,
recreational).
Fire Regime. Defined by type (ground, surface,
or crown fire), frequency (i.e., return interval),
intensity, severity, size, spatial complexity, and
seasonality of fire within a given geographic area or
vegetation type.
Fuel Zone. A defined area within which fuels are
managed to influence fire behavior and/or fire
regimes.
Invasibility or Invasion Potential. The tendency
of a landscape (plant community, ecosystem, or
geographic region) to being invaded.
Invasion. In this handbook, the term is used to
mean both the: 1) spread and establishment of new
species into an area they did not previously occupy;
and 2) increase in dominance (i.e., % density, cover,
and/or biomass) of species previously present but
relatively uncommon within an area.
Invasiveness. The tendency of a species to
successfully invade a landscape.
Section II
Definitions
Fuel types and weather conditions contribute to fire behavior. Photo by M. Weisenberger, USFWS.
6
Invasive Species. Federal Agencies are encouraged
to use the definition of invasive species established
by Executive Order 13112. By this definition invasive
species are both nonnative to the region of interest
and cause environmental or economic harm or harm
to human health.
Management Unit. This term is used in this
handbook as a generic term that refers to a specific
area of interest. These areas of interest typically
include individual postfire management projects,
fire management units (FMUs) or the entire area
encompassed by a fire management plan.
Nonnative. This term refers to species that are not
native to a particular ecosystem. It provides a more
objective criterion than the term weed. Other terms
that have been used as synonyms for nonnative
include alien, exotic, introduced, non-indigenous,
acclimatized, adventive, escaped, feral, foreign,
naturalized, immigrant, and xenobiotic.
Plant Propagules. Parts of plants (i.e., seeds,
rhizomes, tubers, etc.) that are capable of
independent propagation of a new individual.
Plant Resources. Physical resources that can limit
plant growth, primarily including sunlight, water,
and mineral nutrients.
Weed. To qualify as a weed, a plant only needs to
be considered out of place or otherwise unwanted
where it is currently growing. In wildland settings
the term weed is not sufficient and a more specific
definition is required.
A prescribed burn at Chesapeake Marshlands National Wildlife Refuge Complex. Photo by Gerald Vickers,
USFWS.
7
Plant invasions can occur for several reasons. The
type of habitat disturbance, proximity to previously
invaded sites, the number and means available to
spread propagules, altered resource levels, and
disruption of ecological processes have all been
associated with invasive plants spreading into new
areas. All of these factors can be broadly lumped
into two primary variables (See Figure 1):
1. the availability of plant propagules; and
2. the availability of plant resources.
Plant Propagules
When considering plant propagule availability, it is
important to consider the species they represent in
addition to their abundance. If numerous propagules
reach an area, but their specific characteristics are
not adapted to the local environment, they are not
likely to establish a population. Even if propagules
are well suited for establishing and reproducing in
a new environment, they still may not establish a
population if the initial number of propagules is too
small.
In contrast, if many propagules disperse that
are compatible in a new environment, then a new
population is likely to establish. Propagules can
be introduced deliberately (i.e., added to postfire
seeding mixes) or accidentally (i.e., contaminant
species in postfire seeding mixes or straw mulch)
(Fig. 2, link A). Plant propagule numbers can be
reduced by seed predators (i.e., mice, squirrels, and
many birds) or diseases that reduce the reproductive
rates of invasive plants. Established invasive
populations can spread locally, creating a feedback
loop that can become problematic (Fig. 2, link C).
Section III
How Do Plant Invasions Occur?
Plant Propagules
Plant Resources
(includes water, sunlight, and mineral nutrients)
high
invasion
potential
low
invasion
potential
Invasion Potential
Plant Propagules
(number of seeds and other plant parts capable of
reproducing available to establish or increase a population)
Plant Resources
Management Strategy
reduce
resource
availability
reduce
propagule
availability
Figure 1. Main factors affecting plant invasions (adapted from Brooks 2007)
A Recipe for Trouble
Invasive potential is highest when propagules of invasive plants are likely to reach new areas
that offer the combination of resources (soil nutrients, sunlight and moisture) necessary to
establish and compete with native plants for these resources.
8
Resource Availability
In vegetation types where there is frequent natural
disturbance, native vegetation is often able to
recover quickly (i.e., by resprouting or establishing
from seed), and therefore high resource availability
following disturbance may not be a factor in invasive
plant populations becoming established.
In other vegetation types, plant resource availability,
particularly soil nutrients, can affect whether
invasive plants become established. Following a
fire, such resources can be increased directly, (i.e.,
postfire fertilization) or indirectly from the sudden
reduced competition for nutrients after vegetation is
removed (Fig. 2, link B).
Established populations of invasive plants can affect
the supply of resources available (Fig. 2, link D).
For example, some invasive plants might limit the
growth of other species through competition or
inhibition of nutrient uptake.
Processes that reduce plant resource availability,
such as postfire recovery of vegetation, can reduce
invasion potential. As vegetation recovers, resource
uptake increases.
Invasive Species
Abundance
Plant Propagules
Deliberate
Dispersal
Accidental
Dispersal
Plant Resources
Increasing
Input
Decreasing
Uptake
A B
C D
Figure 2. Relationships between propagule availability, resource availability, and invasive
species abundance (adapted from Brooks 2007). Plant propagules (A) and plant resources
(B) both affect the abundance of nonnative plant populations. Once these populations are
established, they can affect plant propagules (C) and plant resources (D).
Regrowth of grass postfire. Photo by M.
Weisenberger, USFWS
Golden crownbeard (Verbesina encelioides) regrowth
following a prescribed burn in pinyon-juniper
habitat. Photo by M. Weisenberger, USFWS.
9
There are three general reasons why management
of invasive plants should be combined with the
management of fires:
1) Fires can promote plant invasions.
2) Fire can be used as a tool to control plant
invasions.
3) Plant invasions can affect fuels, fire behavior,
and fire regimes.
1. Fires Can Promote Plant Invasions
Fires can quickly and dramatically change the
landscape and alter the competitive balance within
the biotic community. Fires consume plant biomass,
which increases the availability of light and reduces
the consumption of soil nutrients, thus increasing
invasion potential during at least the first few
postfire years (Fig. 2).
Most invasions by nonnative plants that have been
reported in the scientific literature report situations
where invasive plants were already established
within landscapes prior to fire. However, disturbance
as a result of a fire event served as an opportunity
for invasive plants to expand their local distributions
and dominance.
Although fire may not be necessary for an invasive
plant to become established in an area, it may allow
the population to expand to the point that it harms
the local ecosystem. From an ecological standpoint
and from the perspective of land managers, such
negative effects represent the area of greatest
concern, and may require a response.
In some native vegetation types that are fire
dependent (i.e., chaparral), increased dominance of
invasive plants may be fleeting; native vegetation
quickly recovers and outcompetes invasive plants.
Where native vegetation is not dependent on fire,
however, the plants do not respond fast enough,
allowing invasive plants to establish and spread
(i.e., some desert shrublands).
Thus, the effects of fire on the spread of invasive
populations can depend on the biology of the native
vegetation, such as the rate at which it recovers
following fire.
Section IV
Why Should the Management
of Invasive Plants and Fires Be
Combined?
Burning piles of Russian thistle (Salsola spp.) to control seed dispersal. Photo by M. Weisenberger, USFWS.
10
2. Fire Can be Used to Control Plant Invasions
Fire has been used since pre-historic times to
manage vegetation for various purposes. Modern
use of fire in wildland areas has focused on
treatments to reduce hazardous fuel loads, restore
historical disturbance regimes, improve forage and
habitat for game and livestock, promote biodiversity,
and manage nonnative invasive plants. Much of
what is currently known about using fire to control
invasive plants has been derived from studies of
cropland systems. Unfortunately, there are many
fundamental differences between cropland and
wildland settings, and our ability to use information
derived from croplands to predict effects that may
occur in wildlands is limited.
Fire has been used effectively to control invasive
late season annual broadleaf and grass species,
particularly yellow starthistle (Centaurea
solstitialis), medusahead (Taeniatherum caput-medusae),
barbed goatgrass (Aegilops triunciallis),
and some brome grasses (Bromus spp.). A limited
number of invasive biennial broadleaves [i.e.,
sweetclover (Melitotus spp.) and garlic mustard
(Alliaria petiolata)], perennial grasses [i.e.,
bluegrasses (Poa spp.) and smooth brome (Bromus
inermis)], and woody species [i.e., brooms (Cytisus
spp.) and Chinese tallow (Triadica sebifera)] have
also been successfully controlled with fire. The most
success comes when fire is integrated with other
control strategies (i.e., herbicides, mechanical)
within an integrated pest management framework.
Most scientific studies have focused on the responses
of specific invasive plants and largely disregard how
other species or the plant community responds as a
whole. This lack of information is a major problem
for land managers because the ultimate reason for
controlling invasives in the first place is to reduce
the dominance of the invasive species and increase
the dominance of the desired native species. Other
objectives may include increasing the status and/
or health of endangered plants, wildlife and insect
populations, and hydrologic function. If these results
are not achieved, then using fire to control target
invasive plant infestations may not be worth the
effort.
Land managers considering using fire to control
invasive plants should be careful to examine the
characteristics of the target invasive species. The
survival rate of plants depends on the degree to
which reproductive tissues are protected from
a fire’s lethally high temperatures. Plants with
reproductive tissues located below ground (i.e.,
seeds or tubers) have higher survival rates and tend
to recover more quickly than plants with vegetative
tissues located above ground (i.e., many shrubs and
trees) (Table 1).
Exposure of regenerative tissue
to damage from fire
Depends on if seeds are
located above-ground on the
parent plant, or at or below
the soil surface after they have
dispersed from the parent plant.
Protected from fire due to soil
insulation above them.
Depends on the percentage of
litter burned and the amount of
smoldering combustion.
Non-fire-adapted shrubs can
be killed by fire due to their
positioning directly in the flame
zone of surface fires.
Can be killed by crown fire
that passes though the plant
canopies, or by surface fire that
girdles the trees.
Life Form (Raunkiaer type)
Annual plants
Bulbs or corms
Rhizomatous plants
Shrubs
Trees
Regenerative tissue
Seeds that reside on or under
the soil surface, or on dead
plants
Living tissue well below the soil
surface
Living tissue just above or
below the soil surface
Living tissue just above the soil
surface
Living tissue well above the soil
surface
Table 1. Effects of fire on different plant life forms (modified from Pyke et al. in prep).
11
3. Plant Invasions Can Affect Fuels, Fire Behavior,
and Fire Regimes
One significant way that invasive plants can affect
the areas they are invading is by changing fuel
properties, which then affects fire behavior (Table
2). If the altered fuel properties remain or increase
after burning, then the fire regimes may be altered.
When altered fire regimes promote the spread of the
invaders that cause the changes in the first place,
then the system is considered to be in an invasive
plant / fire regime cycle.
There are four phases that lead to the establishment
of an invasive plant/fire regime cycle:
Phase 1 involves the initial spread of invasive plants
into an area.
Phase 2 is characterized by establishment of self-perpetuating
populations of the invasive plant.
Phase 3 occurs when the plant spreads beyond the
area first infested, especially disturbed sites into less
disturbed wildland sites, and begins to negatively
impact surrounding native plant communities.
Phase 4 results in fuel properties being changed to
the point that the natural fire regime shifts. If the
new fire regime favors the spread of the invasive
species and reduces the native species, an invasive
plant/fire regime cycle becomes established (Fig. 3).
The most well-known effects of plant invasions
on fire regimes involve those that increase the
frequency, intensity, or length of the fire season.
Collectively, these changes increase what are
commonly referred to as “fire hazards.” For
example, annuals grasses that have invaded
shrublands can increase the frequency of fire and
the length of the fire season in the western United
States, and invaders that increase the woody fuel
load can increase fire intensity in the southeastern
United States. In addition, invading plants with
high tissue flammability (i.e., Eucalyptus) can ignite
easier and burn more intensely.
Plant invasions don’t always increase fire hazards,
and in some cases can actually reduce them.
Invasions can make fuelbeds less flammable
by increasing live fuel moisture, decreasing
fuel continuity, or decreasing fuel loads (Table
2). Examples are harder to find because managers
are generally less concerned about decreased
fire hazards than they are about increased fire
hazards. Potential examples include succulents (i.e.,
cactus and iceplant spp.) invading shrublands and
increasing live fuel moisture, or trees that shade
out surface vegetation and reduce surface fuel
continuity.
Table 2. Primary effects of fuelbed changes on fire regimes.*
Fuelbed Change Fire Regime Change
Increased amount (load) Increased fire intensity and seasonal
burn window; increased likelihood of crown fire
Decreased amount (load) Decreased fire intensity and seasonal
burn window; decreased likelihood of crown fire
Increased horizontal continuity Increased fire frequency and extent
Decreased horizontal continuity Decreased fire frequency and extent
Increased vertical continuity Increased likelihood of crown fire
Decreased vertical continuity Decreased likelihood of crown fire
Change in packing ratio Change in fire frequency, intensity, and
seasonality
Increased plant tissue flammability Increased fire frequency, intensity, and
seasonal burn window
Decreased plant tissue flammability Decreased fire frequency, intensity, and
seasonal burn window
* Modified from Brooks et al. (2004) Table 1
12
As fire regimes and other ecosystem properties
become altered, restoration of pre-invasion
conditions becomes increasingly more difficult and
costly. As the invasive plant infestation spreads and
alters the fire regime, the number of management
actions and cost to restore native ecosystem
functions increases, while the probability of success
decreases. This is because restoration can ultimately
require managing fuel conditions, fire regimes,
native plant communities and other ecosystem
properties, in addition to the invaders that caused
the changes in the first place.
As with other ecological impacts caused by plant
invasions, the most cost effective way to prevent the
establishment of an invasive plant / fire regime cycle
is to take preventative steps early on in the process.
Figure 3. The Invasive Plant/Fire Regime Cycle. Modified from Brooks, et al. (2004).
+ Fire Regime
Fuels
-
Nonnative Plants Nonnative Plants
-
Prescribed burn on Buffelgrass (Pennisetum ciliare) on the Lower Rio Grande NWR. Photo by South Texas
Fire District, USFWS.
13
General guidelines have recently been published
for reducing the spread and dominance of invasive
plants in postfire landscapes (Asher et al. 2001,
Goodwin et al. 2002, Keeley 2003). Collectively
these publications present the following general
recommendations: 1) in response to individual
fires, procedures should be implemented to reduce
inadvertent dispersal of weeds into or within the
burned area; 2) areas where invasive plants of
particular concern are likely to invade or increase in
dominance should be targeted for control efforts;
3) additional revegetation treatments of other
species may be effective at competing with the
target invasives by reducing resource availability;
and 4) National Environmental Policy Act (NEPA)
analyses that are likely to be required prior to
implementing postfire control treatments (i.e.,
herbicide use) should be completed and ready to use
before the fire season. A Pesticide Use Plan (PUP) is
also required before herbicides can be approved for
use.
Although these existing guidelines are helpful, they
are basically checklists of do’s and don’ts, and there
is always the chance that situations may arise where
appropriate guidance is not found on one of the lists.
For example, these guidelines generally focus on fire
suppression and postfire emergency stabilization,
rehabilitation, and restoration activities, and do not
address issues associated with fuels management.
They also do not explicitly integrate fire
management with other land management programs
during the years leading up to and following fires,
nor do they provide specific guidance on prioritizing
which actions may be most effective
in a given situation.
The approach of this handbook is to explain the
primary mechanisms associated with plant invasions
(i.e., resource availability and propagule availability),
and provide examples of how their effects can be
mitigated to minimize invasion potential. With
a basic working understanding of the invasion
Section V
General Operational Guidelines
for Fire Management
Prescribed fire for standing-dead salt cedar. Photo by M. Weisenberger, USFWS.
14
process, a land manager can then better evaluate
how best to integrate fire management actions
(preparedness, suppression, wildland fire use,
prescribed fire, hazardous fuels and post-wildfire
recovery treatments,) into overall land management,
especially when they encounter situations that
are not described in existing guidelines. This
knowledge will also help land managers prioritize
the prevention steps that are most important for
reducing invasion potential in their particular
situation. Examples are provided below that focus
on minimizing plant propagules and resource
availability, using the conceptual model presented
earlier in this document (Figs. 1 and 2). In later
sections the conceptual model is applied to managing
invasive plants in the context of specific fire
management activities.
Minimizing Propagule Availability
Propagule availability can be reduced by ensuring
that seeding treatments do not include species that
may become management problems in the future
(Table 3). Careful consideration of all the problems
associated with introductions of both nonnative
plants, and native species outside of their native
ranges, is the easiest way to reduce invasive species.
Regional lists of invasive plants can be consulted to
help inform fire managers of plants to avoid.
A much greater challenge involves managing
propagule availability due to accidental dispersal of
invasive plants from outside of a management unit
(Table 3). This includes both long-distance dispersal
from outside of the management unit and short-distance
dispersal from adjacent areas, some of
which may lie within the management unit. Sources
of long-distance dispersal include vehicles and other
mechanized equipment, personal items (clothes,
boots, camping equipment), livestock from distant
locations, seed mixes or other vegetation stock, and
erosion control materials from distant locations (i.e.,
soils, rock, hay mulch). These sources are connected
primarily to human transportation, so control can
be focused where they enter the management unit
of interest (i.e., fire camps, erosion control project
areas). Short-distance dispersal from adjacent areas
is much more difficult to manage than long-distance
dispersal, because sources and pathways include all
of the above plus mechanisms such as wind, water,
wildlife, human foot traffic, and other localized
human activities.
The challenge in managing invasions that arise from
outside of a management unit is in detecting and
eradicating the new invaders before they establish
local populations. Necessary steps to detect and
eradicate these new invaders include reducing
dispersal rates, detecting newly established
individuals, and eradicating them. Each of these
steps is potentially very costly, so land managers
need to evaluate how to get the most “bang for the
buck.”
Minimizing Resource Availability
One of the most obvious recommendations for
reducing the likelihood an area will be invaded is
to reduce resource inputs such as adding nitrogen
or phosphorous to the soil (Table 3). Second only
to soil moisture, these nutrients are often the
primary limiting factors of plant growth. It may
seem like a good idea to add these nutrients to give
native vegetation some help as they recover from
a fire event, but unfortunately invasive plants can
often take advantage of large increases in nutrient
availability more effectively than native plants.
Increased invasive plant biomass fueled by nutrient
additions creates additional water demands, and
can lead to increased competition for soil moisture.
For similar reasons, the use of nitrogen-fixing plants
which can increase available soil nitrogen should be
used with caution in revegetation treatments.
Resource availability can also be reduced by
maximizing resource uptake (Table 3). This can
be done by retaining existing vegetation as much
as possible in fuels treatments. For example, if
hazard fuels reduction can be achieved by only
removing ladder fuels, while retaining surface and
canopy fuels, then the potential for subsequent
plant invasion should be lower than if surface
fuels or surface and canopy fuels are removed as
well. Resource uptake can also be accomplished
by adding vegetation in postfire emergency
rehabilitation projects. Carbon sources, such as
organic mulches, can help reduce levels of available
nitrogen.
15
Minimize accidental dispersal
Decontaminate equipment by washing after
use and/or before using at a new geographic
location.
Implement an early detection and rapid
response plan during the first 3 years following
fire to detect and eradicate new populations of
invasive plants within the management unit.
Implement a control and monitoring plan during
the first 3 years following fire to keep existing
invasive plant populations from spreading within
the management unit.
Maximize resource uptake
Reduce loss of vegetation biomass
Promote the re-establishment of desirable
vegetation, either through direct seeding,
planting or implementation of appropriate land-use
regimes (i.e., temporary closures to grazing)
Use carbon sources (i.e., organic mulches) to
reduce available soil nitrogen.
Prevent deliberate dispersal
Carefully evaluate plants considered for
use in revegetation projects to ensure that
they are unlikely to become management
problems in the future.
Minimize resource input
Avoid using nitrogen or phosphorous soil
amendments
Avoid revegetating with nitrogen-fixing
plants (i.e., legumes)
Table 3. General recommendations for minimizing the potential for plant invasions following fire
and fire management actions.
Plant Propagules
Plant Resources
16
Fuels Management
Fuel management practices can also lead to the
proliferation of invasive plants. Fuels management
almost universally involves removal of plant
biomass, which has the potential to increase nutrient
availability and thus increase the likelihood an area
will be invaded. Crews and equipment used for fuels
treatments also have the potential to spread invasive
plants. The window of opportunity for invasions
largely depends on how long it takes for native
vegetation to recover compared to the time invasive
plants become established and spread.
Once established, invasive plants can create new
and unexpected fire hazards that may be even more
difficult to manage. Even fuel treatment specifically
targeted to remove an invasive plant [e.g., salt cedar
(Tamarix spp), or giant reed (Arundo donax)] can
be followed by invasion of another species that, in
turn, could bring additional problems. Monitoring
for new invasive plants following the fuels
treatments may be necessary.
Recommendations for lessening the possibility that
a fuels management treatment may increase the
spread of invasive plants apply to the degree that
project goals can still be achieved (i.e., establishment
of a managed fuel zone). Evaluating what is required
to achieve fuels management goals requires analyses
beyond the scope of this handbook (i.e., fire behavior
modeling).
Plant propagules
If the locations of invasive plants are known prior
to planning a fuel treatment then those locations
can be avoided when possible. The effect of fuels
treatments on nutrient availability may be tempered
by whether or not potentially invasive plants are
nearby. For example, invasive plants may spread
after a fuel treatment where past disturbances left a
large number of invasives, but not where there were
few invasives prior to the treatment.
Unfortunately, invasive plants are often associated
with roads and trails which are commonly used as
anchor points for fuels treatments.
Section VI
Specific Operational Guidelines
for Major Fire Management
Activities
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into the project
site.
Avoid incorporating pre-existing invasive plant
populations into managed fuel zones.
Implement a monitoring and control plan for
invasive plants after the fuels treatments are
applied.
Identify populations of invasive plants within the
project area and focus control efforts in those
areas.
Reducing Resource Availability
Minimize vegetation removal while still
accomplishing fuels management objectives.
Target only the fuel layers that typically
carry fire (i.e., the understory and ladder
fuels in a forest).
Selectively thin to reduce fuel continuity
rather than clear-cut.
Construct fuel breaks no wider than
necessary to accomplish fuel reduction
objectives.
Consider revegetating with less flammable
vegetation following removal of flammable
vegetation.
Cover exposed soil with an organic mulch (i.e.,
hydromulch or chipped fuels).
Incorporate pre-existing fuel breaks, either man-made
or natural (i.e., areas of bare rock), into
managed fuel zones.
Fuels Management Treatments
Best management practices for minimizing the potential for plant invasions
17
Plant resources
Fuels treatments can involve the complete or
partial removal of plant biomass. The greater the
percentage of existing vegetation that is removed,
the greater the potential for spread of invasive
plants. For example, cover of invasive plants
often increases with the proportion of overstory
vegetation that is removed. Also, treatments that
involve both fuels thinning and burning can lead to
higher invasive plant cover than treatments that
include one or the other individually.
In some cases fuels management may include adding
plant cover of low flammability, commonly called
greenstripping. This technique involves the strategic
planting of low flammability plants to prevent or
reduce the rate of fire spread. It has been used
effectively by the Bureau of Land Management
in the Intermountain West. An added benefit of
greenstripping is its potential to reduce nutrient
availability for invasive plants such as cheatgrass
(Bromus tectorum). However, the benefits of adding
potentially aggressive greenstripping plants (which
are typically nonnative) to reduce fire spread and
compete with other undesirable species such as
cheatgrass (Bromus tectorum) must always be
weighed against the potential negative effects
of the species (i.e., competition with natives or
other ecosystem impacts). More information on
greenstripping can be found at http://fresc.usgs.gov/
research.
Fire Suppression
Over time, invasive plants can pose even greater
management challenges than the fires themselves.
The recommendations below are designed to reduce
the likelihood for fire suppression activities to
create opportunities for invasive plants to become
established. These recommendations should only
be considered when there is no immediate threat to
human life and/or property.
Plant propagules
Fire suppression activities are more likely to
influence propagule availability than resource
availability. Fire-fighting crews and their equipment
can move invasive plants as they travel. Firefighters
set up small camps and their equipment largely
consists of personal belongings (i.e., boots, clothes,
sleeping bag, tent), Personal Protective Equipment
(PPE)(i.e., nomex gloves, helmet, goggles, fire pack,
fire shelter), back-pack sprayers, and hand tools
(i.e., shovels, pulaskies, axes, fire rakes, hoes). This
equipment can help spread invasive plants unless
they are cleaned prior to use at other locations. At
the very least, fire-fighters should clean tools, boots,
and tents prior to arriving and leaving a fire site.
Heavy equipment such as bulldozers probably
have the greatest potential for spreading invasives
because they often accumulate significant amounts
of soil and vegetation debris in their undercarriages.
When heavy equipment is used, it should either be
washed prior to transport or washed before it is
allowed to operate in new wildland areas.
Care is taken to limit burning near roads where no invasive plants are present. Photo by M. Weisenberger,
USFWS.
18
Aircraft are often used to transport and disperse
water, foam, or other fire retardant. These aircraft
may be helicopters with buckets, or fixed-wing
aircraft known as tankers or scoopers. There is
some concern that helicopters or scoopers could
carry invasive plants in the water they use. Aquatic
or riparian plants are most likely to be transported
in this manner, and because they are most likely
to be deposited into upland sites where most fires
occur, they would likely not become established.
A significant exception may be the potential for
establishment in springs and creeks that are often
common in upland areas. In general, the likelihood of
moving invasive plants long distances by this method
is probably low because water is typically obtained
from local sources near fires.
Plant resources
Fire suppression activities rarely lead to increased
resource availability, although there are a few
notable exceptions. For example, the use of
phosphate-based fire retardants may lead to
increased growth of invasive plants where phosphate
is a limiting nutrient. The construction of fuelbreaks
and some firelines, both by handcrews and by
heavy equipment, could lead to increased nutrient
availability due to reduced rates of consumption
from plants that are removed to clear the line.
Backing fires could have similar results for the same
reasons. More temporary control lines such as wet
lines or foam lines may be less likely to encourage
plant invasions because the existing vegetation is left
in place.
Emergency Stabilization, Rehabilitation, and
Restoration
Plant propagules
Seed mixes and application equipment are potential
sources for invasive plants. Seed mixes should be
inspected to ensure they are “weed free.” This
may require testing sub-samples to determine
their species composition before they are applied.
Application equipment also needs to be cleaned
before and after use, especially if equipment was
previously used in areas with known invasive plant
infestations.
Plant resources
Plants are mostly seeded after fires to stabilize
soils, but in some cases they are seeded to compete
with and suppress invasive plants. For example,
nonnative wheatgrasses (Agropyron spp.) have often
been planted to suppress the growth of cheatgrass in
the Intermountain West.
Jeff Olson at the Prescribed Fire Training Center. Photo by Greg Zoppetti, USFWS.
19
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into burned areas.
Coordinate with local personnel who know the
locations of invasive plants or who can quickly
survey sites for their presence.
Include warnings to avoid known areas infested
with invasive plants during briefings at the
beginning of each shift.
Avoid establishing staging areas (i.e., fire
camps, helibases) in areas dominated by
invasive plants.
If populations of invasive plants occur within
or near staging areas, flag their perimeters so
that vehicle and foot traffic can avoid them.
Inspect vehicles and equipment and wash them
if they have invasive plants or materials that
may contain invasive plants (i.e., mud) on them.
Inspections should be done when vehicles first
arrive at the fire, and periodically during the
fire as they return from working in the field.
Avoid the use of water from impoundments
infested with invasive plants.
Identify populations of invasive plants within the
burned area and focus postfire control efforts in
those areas.
For pre-planned wildland fire, environmental
assessments should at least document the
locations of major populations of invasive plants
within the proposed burn unit and evaluate the
potential for the burn prescription to increase
their dominance and spread. If the potential is
high, either remove those areas from the burn
unit or develop a postfire mitigation plan.
Implement a postfire monitoring and control
plan for invasive plants. Focus on populations of
invasive plants known to exist before the fire and
on areas of significant fire management activity
during the fire (i.e., fire camps, dozer lines).
Reducing Resource Availability
Minimize vegetation removal in the construction
of control lines.
Use wet lines and foam lines as much as
possible.
Use narrow handlines rather than broad dozer
lines or blacklines.
Minimize the use of nitrogen and phosphate-based
retardants, except where their use
eliminates the need for vegetation removal.
Tie control lines into pre-existing fuel breaks and
managed fuel zones.
During mop up, scatter organic matter back over
exposed soil where control lines were established.
Fire Suppression
Best management practices for minimizing the potential for plant invasions
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel do
not spread invasive plants into the project site.
Revegetate with native species, or nonnatives that
are not likely to become invasive.
Test seed mixes or other types of revegetation
materials to ensure that they do not contain
invasive plants as contaminants.
Implement a monitoring and re-treatment plan
for invasive plants after the initial treatments are
applied.
Reducing Resource Availability
Vegetate with fast-growing but non-invasive plants
to increase the uptake of resources that would
otherwise be utilized by invasive plants.
Cover exposed soil with an organic mulch (i.e.,
hydromulch or chipped fuels).
Focus efforts on reducing resource availability in
areas with sources of invasive plants.
Emergency Stabilization, Rehabilitation, and Restoration
Best management practices for minimizing the potential for plant invasions
20
Postfire Land-Use Regimes
Plant propagules
Any land-use activity increases the chance for
accidental introduction of invasive plant, so
reducing these activities can lessen the potential
for plant invasions. Invasive plants can be moved
by many ways, including people, stock animals,
pets, vehicles, equipment, and livestock feed just to
name a few. Thus, any person or anything traveling
into a recently burned area should be considered
a potential vector. It is much more cost effective to
prevent plant invasions than to manage them after
invasive plant populations are firmly established.
Plant resources
There are often significant demands to quickly
re-establish prevailing land-use activities following
fires. If these activities affect resource availability,
they may increase the likelihood an area will be
infested by invasive plants. For example, livestock
grazing is a common land-use on public lands,
and one of its main effects is the removal of plant
biomass. Biomass removal generally reduces levels
of competition and increases the availability of soil
nutrients, thus increasing the potential for invasive
plants to move into an area.
If it is possible to target grazing on invasive plants,
then it may help counteract the effects of increased
soil nutrients. However, the ability to control
what livestock eat makes focusing on undesirable
vegetation very difficult. In addition, repeated
grazing in focused areas over longer periods of
time can lead to other problems such as soil erosion
and loss of native species diversity, and even short
periods of deferred grazing may allow nonnatives to
rise to dominance.
Postfire Land-Use Regimes
Best management practices for minimizing the potential for plant invasions
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into burned areas.
Consider temporary closure of public access to
burned areas to of invasive plants.
Consider using livestock grazing to target
invasive plants for short-term control.
Reducing Resource Availability
Minimize land uses that may reduce vigor of
resprouting of native plants (i.e., livestock
grazing).
Treating invasive plants with fire. Photo by M. Weisenberger, USFWS
21
Monitoring management actions should focus on
responses of immediate interest, but should also
consider abiotic factors. In most cases, monitoring
is associated with the management action of interest
(i.e., the influence of fuels management on fuel
characteristics). Monitored responses will sometimes
extend to secondary effects (i.e., the influence of
fuels management on fuel characteristics, and
ultimately on fire behavior and fire regimes). At a
minimum, monitoring needs to determine whether
objectives of the management action have been
achieved.
Commonly used agency monitoring publications,
described in Table 4, outline vegetation monitoring
methodology, although none specifically address
invasive plants. Monitoring plans should include
the following elements: objectives, stratification,
controls, random sampling, data quality, and
statistical analysis. All of these topics, except for
controls, are discussed at length in the publications
listed in Table 4; only two monitoring publications
(USDI National Park Service 2003, Lutes et al. 2006)
cover all six monitoring elements.
Section VII
Effectiveness Monitoring
Table 4. Agency publications on monitoring.
Monitoring Publication Covers Fire Monitoring Associated Software
Fish and Wildlife Service
Fuel and Fire Effects Monitoring Guide Yes No
(USDI Fish and Wildlife Service 1999)
Bureau of Land Management No No
Sampling Vegetation Attributes
(Interagency Technical Reference 1999)
National Park Service
Fire Monitoring Handbook Yes Yes
(USDI National Park Service 2003)
Forest Service
FireMon: Fire Effects Monitoring and Yes Yes
Inventory Protocol (Lutes et al. 2006)
Agricultural Research Service
Monitoring Manual for Grassland, No Yes
Shrubland, and Savanna Ecosystems
(Herrick et al. 2005a,b)
22
Asher, J.E., S. Dewey, C. Johnson and J. Olivarez.
2001. Reducing the spread of invasive exotic
plants following fire in western forests, deserts,
and grasslands (abstract). In: Galley KEM and
Wilson TP (Eds) Proceedings of the Invasive
Species Workshop: the Role of Fire in the Control
and Spread of Invasive Species. Fire Conference
2000: the First National Congress on Fire
Ecology, Prevention, and Management, pp 102-
103. Tall Timbers Research Station, Tallahassee,
FL.
Brooks, M.L. C.M. D’Antonio, D.M. Richardson,
J. Grace, J. J. Keeley, DiTomaso, R. Hobbs, M.
Pellant, and D. Pyke. 2004. Effects of invasive
alien plants on fire regimes. BioScience 54:677-
688.
Brooks, M.L. 2007. Effects of land management
practices on plant invasions in wildland areas.
Pages 147-162 in: W. Nentwig (ed.) Biological
Invasions. Ecological Studies, Vol. 193, Springer,
Heidelberg, Germany.
Champion, P.D., and J.S. Clayton. 2001. A weed
risk assessment model for aquatic weeds in
New Zealand. Pages 194-202 in R.H. Groves,
F.D. Panetta, and J.G. Virtue (eds.), Weed risk
assessment. CSIRO, Collingwood, Victoria,
Australia.
D’Antonio, C.M. and P.M. Vitousek. 1992. Biological
invasions by exotic grasses, the grass/fire cycle,
and global change. Annual Review of Ecology and
Systematics. 23:63-87.
D’Antonio, C.M. 2000. Fire, plant invasions and
global changes. In: H. Mooney and R. Hobbs
(Eds). Invasive species in a changing world, pp.
65-94. Island Press, Covela.
DiTomaso, J.M., M.L. Brooks, E. B. Allen, R.
Minnich, P. M. Rice, and G. B. Kyser. 2006. Control
of invasive weeds with prescribed burning. Weed
Technology 20:535-548.
DiTomaso, J. M. and D. W. Johnson (Eds.). 2006.
The Use of Fire as a Tool for Controlling Invasive
Plants. Cal-IPC Publication 2006-01. California
Invasive Plant Council: Berkeley, CA. 56 pp.
Fox, A. M., D.R. Gordon, J.A. Dusky, L. Tyson,
and R.K. Stocker. 2001. IFAS assessment of
non-native plants in Florida’s natural areas.
SS-AGR-79. Agronomy Department, Florida
Cooperative Extension Service, Institute of
Food and Agricultural Sciences, University of
Florida. Available online at http://agronomy.ifas.
ufl.edu/docs/IFASAssessment2001.pdf
Galley, K. E. and Wilson. 2001. Proceedings of the
Invasive Species Workshop: The Role of Fire in
the Control and Spread of Invasive Species. Fire
Conference 2000: The first National Congress on
Fire Ecology, Prevention and Management, San
Diego, CA, Misc. Pub No. 11.
Godwin, K., R. Sheley, and J. Clark. 2002. Integrated
Noxious Weed Management After Wildfires.
Montana State University Extension Service. 26
pp. Available online at www.montana.edu/wwwpb/
pubs/eb160.html.
Heffernan, K.E., P.P. Coulling, J.F. Townsend,
and C.J. Hutto. 2001. Ranking invasive exotic
plant species in Virginia. Natural Heritage
Technical Report 01-13. Virginia Department of
Conservation and Recreation, Division of Natural
Heritage: Richmond, Virginia. 27 pages. Avalable
online at http://www.dcr.state.va.us/dnh/rankinv.
pdf
Herrick, J.E., J.W. Van Zee, K.M. Havstad, L.M.
Burkett, and W.G. Whitford. 2005a. Monitoring
Manual for Grassland, Shrubland, and Savanna
Ecosystems. Volume 1: quick start. USDA-ARS
Jornada Experimental Range. Las Cruces, NM.
36 p.
Herrick, J.E., J.W. Van Zee, K.M. Havstad, L.M.
Burkett, and W.G. Whitford. 2005b. Monitoring
Manual for Grassland, Shrubland, and Savanna
Ecosystems. Volume 2: design, supplementary
methods and interpretation. USDA-ARS Jornada
Experimental Range. Las Cruces, NM. 200 p.
Hiebert, R.D., and J. Stubbendieck. 1993. Handbook
for Ranking Exotic Plants for Management
and Control. U. S. Department of the Interior,
Natural Resources Report NPS/NRMWRO/
NRR-93/08. National Park Service, Natural
Resources Publication Office, Denver, CO.
Interagency Technical Reference. 1999. Sampling
Vegetation Attributes. BLM Technical Reference
1734-4. National Business Center, Denver, CO.
158 p
Keeley, J.E. 2003. Fire and invasive plants in
California ecosystems. Fire Management Today
63:18-19
Klinger, R.E. Underwood, P. Moore. 2006. The role
of environmental gradients in non-native plant
invasion into burnt areas of Yosemite National
Park, California. Diversity and Distributions 12:
139-156.
Section VIII
Bibliography
23
Lutes, D. C., R.E. Keane, J.F. Caratti, C.H. Key,
N.C. Benson, S. Sutherland, and L.J. Gangi.,
2006. FIREMON: Fire Effects Monitoring and
Inventory System. Gen. Tech. Rep. RMRS-GTR-
164-CD. For Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain
Research Station. 1 CD. 400 p.
Morse, L.E., J.R. Randall, N. Benton, R. Hiebert,
and S. Lu. 2004. An invasive species assessment
protocol: Evaluating non-native plants for their
impact on biodiversity. Version 1, NatureServe,
Arlington Virginia. Available online at http://www.
natureserve.org/getData/plantData.jsp.
Orr, R.L., S.D. Cohen, and R.L. Griffin. 1993.
Generic nonindigenous pest risk assessment
process. U.S. Department of Agriculture,
Washington, D.C.
Pyke, D., M. Brooks, C.M. D’Antonio. In prep.
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framework for predicting the control or
enhancement of plants using fire. Restoration
Ecology.
Thorp, J.R., and R. Lynch. 2000. The determination
of weeds of national significance. National Weeds
Strategy Executive Committee, Launceston,
Australia. Avalable online at http://www.weeds.
org.au/docs/WONS/
USDI Fish and Wildlife Service. 1999. Fuel and Fire
Effects Monitoring Guide. http://www.fws.gov/
fire/downloads/monitor.pdf. Accessed 9/22/06.
USDI National Park Service. 2003. Fire Monitoring
Handbook. Fire Management Program Center,
National Interagency Fire Center. Boise, ID.
274 p.
Virtue, J.G., R. H. Groves, and F.D. Panetta. 2001.
Towards a system to determine the national
significance of weeds in Australia. Pages 124-152
in R.H. Grove, F.D. Panetta, and J.G. Virtue,
eds., Weed risk assessment. CSIRO, Collingwood,
Victoria, Australia.
Warner, P.J., C.C. Bossard, M.L. Brooks,
J.M. DiTomaso, J.A. Hall, A. Howald, D.W.
Johnson, J.M. Randall, C.L. Roye, M.M.
Ryan, and A.E. Stanton. 2003. Criteria for
Categorizing Invasive Non-Native Plants that
Threaten Wildlands. California Exotic Pest Plant
Council and Southwest Vegetation Management
Association. 24 pp. (http://ucce.ucdavis.edu/files/
filelibrary/5319/6657.doc).
Weiss, J., and D. McLaren. 1999. Invasive
Assessment of Victoria’s State Prohibited,
Priority and Regional Priority Weeds. Keith
Turnbull Research Institute, Agriculture Victoria,
Frankston, Victoria, Australia. 16 pp.
Wirth, Troy A., and Pyke, David A. 2007, Monitoring
post-fire vegetation rehabilitation projects-A
common approach for non-forested ecosystems:
U.S. Geological Survey Scientific Investigations
Report 2006-5048, 36 pp.
Zouhar, K., J. Kapler Smith, S. Sutherland, and
M. L. Brooks. (eds.) 2008. Wildland fire in
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Service, Rocky Mountain Research Station.
355 pp.
Using drip torches to apply fire to buffelgrass on the Lower Rio Grande Valley National Wildlife
Refuge. Photo by South Texas Fire District, USFWS.
24
Federal Mandates
The following is a chronological list of federal laws,
executive orders and management plans pertaining
to invasive plant control with fire management
activities on federal lands. Federal Acts may be
found on-line at: http://www.gpoaccess.gov/uscode/
search.html; or Public Laws (since 1994) at: http://
www.gpoaccess.gov/plaws/search.html.
National Wildlife Refuge System Administration
Act, as amended
This act establishes the Fish and Wildlife Refuge
System. This act requires the agency to administer
lands to provide for the conservation of fish,
wildlife, plants and their habitats and to ensure that
biological integrity and diversity are maintained.
National Environmental Policy Act (1970)
This act requires government agencies to consider
the environmental effects of their actions through
the preparation of appropriate NEPA documents
(i.e., EAS, EA or EIS). Effects of nonnative species,
if harmful to the environment, would be included
in NEPA analysis. In emergency situations, NEPA
procedures that would normally be required may
be negotiated with the Council of Environmental
Quality.
Endangered Species Act (1973)
This Act protects federally listed Threatened and
Endangered species. When nonnative invasive
species threaten a Threatened or Endangered
species, this Act could be used to justify treatment
of the infestation.
Federal Land Policy and Management Act (1976)
This act establishes public land policy and
guidelines for its administration and to provide for
the management, protection, development, and
enhancement of public lands.
Lacey Act (1981)
Under this Act it is unlawful to import, export,
transport, buy or sell fish, wildlife and plants taken
or possessed in violation of federal, state or tribal
laws.
Appendix A.
Laws, Policies And Planning Documents
Guiding the Management of Invasive
Plants and Fire
Using fire as a beneficial tool to treat invasive plants. Photo by M. Weisenberger, USFWS
25
Hawaii Tropical Forest Recovery Act (1992)
This Act establishes the Hawaii Tropical Forest
Recovery Task Force to draft a plan for rejuvenating
Hawaii’s tropical forests.
Executive Order 13112 (1999)
This Order defines invasive species as an alien
species whose introduction does or is likely to cause
economic or environmental harm or harm to human
health. It directs all federal agencies to address
invasive species concerns and refrain from actions
that are likely to increase invasive species problems.
This Order also established the National Invasive
Species Council and the development of a National
Invasive Species Management Plan to better
coordinate efforts among federal agencies.
Plant Protection Act (2000)
This Act replaced many previous invasive plant
species acts including the Federal Noxious Weed
Act, the Plant Quarantine Act, the Federal Plant
Pest Act and other related statutes and primarily
applies to USDA, but authorizes APHIS to take both
emergency and extraordinary actions to address
incursions of noxious weeds which can be regulated
on federal lands.
Noxious Weed Control and Eradication Act (2004)
This Act is an amendment to the Plant Protection
Act above and provides for the provision of
funds through grants and agreements to weed
management entities for the control and eradication
of noxious weeds.
National Invasive Species Council Management
Plan (2008)
The National Invasive Species Council was
established by Executive Order 13112. One of its
directives under the EO is to prepare a management
plan for invasive species that will provide guidance
for all federal agencies over a four year period.
Department of Interior Policy
The Departmental Manual (DM) has several policies
addressing invasive species management issues. The
following is numerically ordered list of DM policies
that relate directly or indirectly to fire and invasive
species management activities. DM policies may be
found on-line at: http://elips.doi.gov/app_dm/index.
cfm?fuseaction=home
516 DM 2 - Initiating the NEPA Process (2005)
This purpose of this Chapter is to provide
instructions for implementing CEQ regulations that
pertain to initiating the NEPA process. Appendix
2.12. states that the introduction of invasive species
is an extraordinary circumstance to a Categorical
Exclusion according to the Federal Noxious Weed
Control Act and Executive Order 13112.
Appendix 1 provides a list of management actions
that are DOI Categorical Exclusions pursuant
to 516 DM 2.3(A). Included in these actions
are: 1.6 - non-destructive inventory, research
and monitoring activities, 1.12 - Hazardous
fuels reduction activities using prescribed fire
not to exceed 4,500 acres, and 1.13 - Post-fire
rehabilitation activities not to exceed 4,200 acres.
Appendix 2 lists Extraordinary Circumstances
for some actions covered under Categorical
Exclusions. Relevant actions include: 2.3 - Have
highly controversial environmental effects, 2.4 -
Involve unknown environmental risks, and 2.12
- Contribute to the introduction or spread of non-native
invasive species.
516 DM 8 - Managing the NEPA Process -
U.S. Fish and Wildlife Service (2004)
This Chapter provides supplementary requirements
for implementing provisions of 516 DM 1 through
6 within the Department’s U.S. Fish and Wildlife
Service. Section 8.5 lists important Categorical
Exclusions for FWS activities. Relevant Categorical
Exclusions that may cover some fire and invasives
management actions include:
8.5.B(1): Research, inventory, and information
collection activities.
8.5.B(3): The construction... structures and
improvements for the restoration of wetland,
riparian, instream, or native habitats, which result
in no or only minor changes in the use of the
affected local area.
8.5B(4): The use of prescribed burning for habitat
improvement purposes.
8.5B(5): Fire management activities, including
prevention and restoration measures.
8.5B(6): The reintroduction or supplementation
(e.g., stocking) of native, formerly native, or
established species into suitable habitat within
their historic or established range.
517 DM 1 Integrated Pest Management Policy
(2007)
This policy updates the Integrated Pest
Management (IPM) policy to make it consistent
with current laws, contemporary science, and other
authorities. The revised policy addresses the IPM
process and pest management tools, including
pesticides and biological control agents.
522 DM Implementation of Adaptive
Management Policy (2008)
This Chapter provides guidance to help Agencies
incorporate adaptive management strategies
into their land and resource management
decisions. Section 1.5 (B) requires offices to conduct
appropriate monitoring to determine resource status
and evaluate progress toward achieving objectives.
606 DM 2 Soil and Moisture Conservation Policy
(1971)
This policy affirms that the purpose of the soil
conservation program is to restore and maintain
soil properties for optimal conditions. Both burning
26
and weed control are listed as an appropriate
soil and moisture conservation activities for site
improvement (Section 2.2.B.1).
609 DM 1 Weed Control Program Policy (1995)
This policy defines undesirable plants/weeds as
noxious when they interfere with man’s activities
or welfare. It is DOI policy to control undesirable
plants on lands under its jurisdiction. Further,
programs within DOI for the control of undesirable
plants will incorporate integrated pest management
practices. DOI Bureaus will coordinate their
integrated pest management activities with other
federal and non-federal agencies where possible.
At the Bureau level, each Bureau is responsible for
planning, funding, implementing, and overseeing
integrated pest management programs. This policy
establishes the DOI weed control committee with
representatives from each bureau and is charged
with overall interdisciplinary program development.
620 DM 2 Burned Area Rehabilitation Policy
(2004)
This chapter provides the Departmental Policy for
the Emergency Stabilization and Rehabilitation
on Bureau lands and Indian Trust Lands following
wildland fires. Specifically, Section 3.8E states that
exotic species introductions as a part of seeding in
burned areas are restricted with exceptions from
the Secretary of the Interior. Section 3.2.W. states
that Executive Order 13112 is an authority for
conducting BAER activities. Other references to the
prevention of invasive species are found throughout
this Chapter.
Fish and Wildlife Service Policy
There are many citations throughout the Fish and
Wildlife Service Manual (FW), Administrative
Manual (AM) and Refuge Manual (RM) that
describe FWS policy as it relates to invasive species.
The following is a list of FWS and NWRS policies
directly or indirectly related to invasive species and
fire management activities. FWS policies may be
found on-line at: http://www.fws.gov/policy/manuals/.
Environment 30 AM 12 Pest Management Policy
and Responsibilities
This policy affirms that the FWS will use
integrated pest management in its planning of pest
management actions. Section 12.5 (B) lists burning
as a type of cultural control that can be used to
reduce pest populations.
052 FW 4 Planning and Management
This policy states that the ecosystem approach
concept to fish and wildlife management will be
implemented. Section 1.8.B.2.a.vii. states that
goals should include exotic species concepts when
developing plans.
Fire can be an effective tool to restore habitat on a landscape scale. Photo by M. Weisenberger, USFWS.
27
095 FW 3 Emergency Operations
This policy involves fire management activities.
Section 3.9.C.1.a. describes fire damage restoration
to include the use of herbicides, and other site
preparation activities to reduce weed competition
prior to seeding burned areas for restoration.
Section 3.9.B.2.E states that the FWS will minimize
the establishment of nonnative species in BAER
activities to prevent unacceptable degradation
to burned areas, Section 3.D.1.C. states that
fuels management projects will minimize the
establishment of invasive species.
601 FW 1 National Wildlife Refuge System
Mission and Goals and Refuge Purposes
This policy reiterates that the overarching goal of
the NWRS is to conserve a diversity of fish, wildlife,
and plants and their habitats by focusing on native
species.
601 FW 3 Biological Integrity, Diversity and
Environmental Health
This policy involves maintaining and restoring the
biological integrity, diversity and environmental
health of NWRs. Section 3.10.B3 states that the
FWS strives to minimize the spread of invasive
species; Section 3.11.B. states that the FWS should
use physical structures and chemical applications
to manage for biological diversity and eliminate
invasive species; Section 3.14.F. states that the
FWS supports the reintroduction of extirpated
native species to control invasive species if needed;
Section 3.16.A. states invasive species should not
be introduced, populations should be detected and
controlled through integrated pest management
strategies including mechanical, chemical, biological,
and cultural control methods.
602 FW 3 Exhibit 2 Comprehensive Conservation
Planning
This exhibit describes the statutes that should be
considered in the CCP process and identifies the
Noxious Weed Act as a mandate.
603 FW 1 Appropriate Refuge Uses
This policy states that invasive species control is
an accepted refuge management activity that is
included in appropriate refuge uses (Section 1.2.B).
603 FW 2 Compatibility
This policy states that refuge management activity
such as invasive species control does not require a
compatibility determination (Section 2.10.A).
620 FW 1 Habitat Management Plans
This policy describes guiding principles for the
development of habitat management plans on
refuges. Section 1.4.E defines the term invasive
species for habitat management plans; Section 1.7G
describes guiding principles which should include
invasive species management. Section 1.7.G. also
states that an integrated pest management plan will
be used to describe activities related to the control of
invasive species
640 FW 1 Partners for Fish and Wildlife Program
This chapter describes the implementation of the
Partners for Fish and Wildlife Program. Section
1.13.I on Service fire management policy recognizes
that prescribed fire is an important and acceptable
tool to remove exotic species and gives guidelines for
using Partners funding for prescribed burning.
7 RM 8 Exotic Species Introduction and
Management
This policy affirms that the NWRS exists for the
protection and management of plants and animals
native to the United States. It outlines the special
circumstances under which the continued existence
of nonnative plants or animals may be permitted.
In particular, it discusses the requirements for
releasing biocontrols onto a refuge.
7 RM 14 Pest Control
Although this policy deals largely with the use of
pesticides on refuges, it does affirm that one of
the objectives of pest management activities on
refuges is to control exotic species and allow normal
populations of native species to exist.
The National Strategy for Management of
Invasive Species
National Wildlife Refuge System (2003)
This document was developed by a Fulfilling the
Promise Team with the support of the regional
refuge chiefs. It outlines a comprehensive strategy
for dealing with the critical problem of invasive
species on National Wildlife Refuges. The plan
was developed in the context of Executive Order
13112 and the National Invasive Species Council
management plan. A copy of this strategy may be
found on-line at: http://www.fws.gov/invasives/pdfs/
NationalStrategyFinalRevised05-04.pdf
U.S. Department of the Interior
U.S. Fish & Wildlife Service
http://www.fws.gov
March 2009

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Fire Management
and Invasive Plants
A Handbook
U.S. Fish & Wildlife Service
Cover: Prescribed burn to treat salt cedar
(Tamarix spp.). Photo by M. Weisenberger, USFWS.
by Matthew Brooks
U.S. Department of the Interior
U.S. Geological Survey
Western Ecological Research Center
and
Michael Lusk
National Wildlife Refuges
Invasive Species Coordinator
4401 N. Fairfax Dr., Rm. 655B
Arlington, VA 22203
Fire Management
and Invasive Plants
A Handbook
Acknowledgements:
We would like to thank the following people for their
contributions to the publication of this Handbook.
Jenny Ericson for general project oversight.
Karen Murphy, Fred Wetzel, Bill Leenhouts, and
Karen Phillips for their numerous reviews of the
document and resulting edits. Mara Weisenberger
for proofreading and editing the document and
supplying photos. Sue Wilder for gathering
information on fire and invasive species policy.
Karen Miranda Gleason and Kevin Kilbride for
providing background information. Brian McManus,
Chris Pease, Art Latterell and Andy Loranger for
their continued support of the project and help in
moving the project to completion. Aaron Fester for
editing the document to make it more accessible to
the field. Mark Newcastle for layout, format and
design. The compilation and synthesis of information
and the final production of this Handbook was
supported by funding from the U.S. Fish and
Wildlife Service, National Refuge System, Branch of
Fire Management; U.S. Geological Survey, Invasives
and Ecosystems programs; and numerous projects
administered by the Joint Fire Science Program,
most notably project #00-1-2-04.
Suggested citation:
Brooks, M. and M. Lusk. 2008. Fire Management
and Invasive Plants: a Handbook. United States
Fish and Wildlife Service, Arlington Virginia, 27
pp.
Table of Contents
Executive Summary and General Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Section I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Introduction
Section II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Definitions
Section III. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
How Do Plant Invasions Occur?
Section IV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Why Should the Management of Invasive Plants and Fires Be Combined?
Section V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
General Operational Guidelines for Fire Management
Section VI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Specific Operational Guidelines for Major Fire Management Activities
Section VII. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Effectiveness Monitoring
Section VIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Bibliography
Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Laws, Policies And Planning Documents
Guiding the Management of Invasive Plants and Fire
1
Fire management can help maintain natural
habitats, increase forage for wildlife, reduce fuel
loads that might otherwise lead to catastrophic
wildfire, and maintain natural succession. Today,
there is an emerging challenge that fire managers
need to be aware of: invasive plants. Fire
management activities can create ideal opportunities
for invasions by nonnative plants, potentially
undermining the benefits of fire management
actions.
This manual provides practical guidelines that fire
managers should consider with respect to invasive
plants.
What’s the Link Between Fire and Plant Invasion?
The growth and spread of any plant species depends
on two main factors:
1) plant propagule availability: the abundance of
seeds and other plant propagules (i.e., parts of a
plant that can produce a new individual), and
2) plant resource availability: the amount and quality
of resources (sunlight, soil nutrients, etc.) that newly
arrived propagules need to grow.
Postfire conditions can create ideal habitat for
certain plants. When those conditions are created
within easy range of the propagules of invasive
plants, the situation is ripe for an invasion. The
graphs below (Box 1.) illustrate both invasion
potential and subsequent management strategy
based on the relationship between plant propagule
availability and resource availability.
What Can Fire Managers Do?
The best approaches fire managers can take for
reducing the potential for invasive plant infestations
are to minimize or eliminate the introduction of
invasive plant propagules into fire management
areas and minimize the amount of resources
available to any such plants that might find their way
into the burned area.
Primary Guidelines
At a minimum, the following should be applied in all
situations:
Prevent Dispersal of Invasive Plants:
••Locating fire camps and staging areas in areas
relatively free of weeds and other invasive plants.
Plant Propagules
Plant Resources
high
invasion
potential
low
invasion
potential
Invasion Potential
Plant Propagules
Plant Resources
management
response
unnecessary
Management Strategy
reduce
resource
availability
reduce
both
factors
reduce
propagule
pressure
Box 1. Invasion potential and management strategy.
Executive Summary and
General Recommendations
2
••Washing vehicles and equipment before and after
being used within a project area (i.e., treatment
area, fireline).
••Ensuring that any revegetation (i.e., seed mixes)
or other organic material (i.e., straw mulch) that
is introduced into the project area is certified as
weed-free.
Minimize Resources Available to Invasive
Plants:
••Remove only enough vegetation to accomplish
the management objectives (i.e., creating a
managed fuel zone, constructing a fireline).
••As an alternative to vegetation removal, consider
replacing highly flammable vegetation with less
flammable vegetation when creating a managed
fuel zone.
Are Additional Steps Necessary?
The above guidelines should be applied to all
situations. You will need more information––
primarily regarding propagule and resource
availability––to determine if additional preventative
methods are necessary. In these cases, fire
managers need to prioritize which actions will
provide the best results, and these actions can vary
depending on the circumstances associated with
each individual fire. Consult the reference guide
below that includes additional site-based guidelines
providing more specific recommendations associated
with four typical scenarios.
1. Low Propagule Availability
and Low Resource Availability
No major management actions are warranted.
Low propagule availability can occur if survey
data indicate few populations and low densities of
invasive plants.
Low resource availability can occur where
vegetation loss is relatively low and/or recovery
potential is high. Examples include fuels projects
that thin but do not completely remove vegetation
or fires where burn severities are relatively low
and/or native vegetation cover is expected to
reestablish within a few years.
Almost all management actions have the potential
to cause unexpected and undesirable effects (i.e.,
seed mixes or straw mulch can be contaminated
by unwanted species), so they should only be
implemented if there are compelling reasons to
do so.
2. Low Propagule Availability
and High Resource Availability
Management actions should focus on minimizing
resource availability.
In this scenario resource availability is high, such
as following complete removal of vegetation to
create managed fuel zones or after a high severity
fire. If the area has high levels of resource
availability, then it may be most effective to focus
management efforts on reducing these factors.
However, the absence or rarity of invasive plants
may warrant little or no additional management
response.
3. High Propagule Availability
and Low Resource Availability
Management actions should focus on minimizing
propagule availability.
If the area in question is in proximity to large
source populations of invasive plants, then
management of propagule dispersal into the area
may be the best strategy. Focus on preventing the
dispersal of propagules into the project areas, and
on eradicating newly established individuals and
populations at the edges of the invasive plants’
range. Follow-up monitoring is always required to
determine if re-treatment is needed.
4. High Propagule Availability
and High Resource Availability
Management actions are warranted to minimize
both plant propagule availability and resource
availability as discussed above.
3
Using fire as a tool to manage at the landscape scale. Photo by M. Weisenberger, USFWS.
Low Propagule/Low Resource
No major management actions are warranted
where
Vegetation loss from fire is low
Native vegetation is expected to return
quickly
High Propagule/Low Resource
Management actions should focus on
minimizing propagule availability where
Area in question is in proximity to large
source populations of invasive plants.
Low Propagule/High Resource
Management actions should focus on
minimizing resource availability where
Native vegetation is completely removed
but invasive plants are rare or absent from
the area.
High Propagule/High Resource
Management actions are warranted to
minimize both plant propagule availability
and resource availability as discussed above
where
Native vegetation is completely removed
(fuel load management, severe wildfire), and
invasive propagules have access to the area.
Box 2. Summary of Guidelines.
4
The purpose of this manual is to provide practical
guidelines for fire managers to effectively integrate
invasive plant management activities into their
fire management programs. Traditionally, fire
management and invasive plant management
have been conceived and implemented as separate
programs. This manual is designed to help land
managers bridge the gap between these two
disciplines, and in particular give fire managers
the tools they need to integrate invasive plant
management strategies into the fire planning
process. Although this handbook is tailored
specifically for the fire management community
within the National Wildlife Refuge System of the
U.S. Fish and Wildlife Service, it is also relevant
to other agencies and organizations that manage
wildland fire.
Section I
Introduction
U.S. Fish and Wildlife Service fire crew conducting a prescribed burn. USFWS.
5
One of the potentially confusing aspects of invasive
plant management relates to definitions. Many
different terms have been associated with plants
that are land management problems or deemed
undesirable for one reason or another. Because
these terms are often used interchangeably in
management documents, and their usage can be
confusing, some of the most commonly used terms
are defined below. Several commonly used fire
management terms are also described to encourage
consistency across programs.
Accidentally Introduced. Species that dispersed
without intentional human intervention, such as
contaminants of plant stock or planting materials
(i.e., mulches), or by attaching to equipment, shoes,
or animals.
Deliberately Introduced. Species that were
intentionally transported to and cultivated in new
areas for various purposes such as livestock forage,
erosion control, or ornamental horticulture, but
then subsequently spread into areas where they are
unwanted.
Fire Behavior. The rate of spread, residence time,
flame length, and flame depth of an individual fire.
Fire Hazard. Fuel conditions that are deemed
hazardous to human life, property, or valued land
management resources (i.e., natural, cultural,
recreational).
Fire Regime. Defined by type (ground, surface,
or crown fire), frequency (i.e., return interval),
intensity, severity, size, spatial complexity, and
seasonality of fire within a given geographic area or
vegetation type.
Fuel Zone. A defined area within which fuels are
managed to influence fire behavior and/or fire
regimes.
Invasibility or Invasion Potential. The tendency
of a landscape (plant community, ecosystem, or
geographic region) to being invaded.
Invasion. In this handbook, the term is used to
mean both the: 1) spread and establishment of new
species into an area they did not previously occupy;
and 2) increase in dominance (i.e., % density, cover,
and/or biomass) of species previously present but
relatively uncommon within an area.
Invasiveness. The tendency of a species to
successfully invade a landscape.
Section II
Definitions
Fuel types and weather conditions contribute to fire behavior. Photo by M. Weisenberger, USFWS.
6
Invasive Species. Federal Agencies are encouraged
to use the definition of invasive species established
by Executive Order 13112. By this definition invasive
species are both nonnative to the region of interest
and cause environmental or economic harm or harm
to human health.
Management Unit. This term is used in this
handbook as a generic term that refers to a specific
area of interest. These areas of interest typically
include individual postfire management projects,
fire management units (FMUs) or the entire area
encompassed by a fire management plan.
Nonnative. This term refers to species that are not
native to a particular ecosystem. It provides a more
objective criterion than the term weed. Other terms
that have been used as synonyms for nonnative
include alien, exotic, introduced, non-indigenous,
acclimatized, adventive, escaped, feral, foreign,
naturalized, immigrant, and xenobiotic.
Plant Propagules. Parts of plants (i.e., seeds,
rhizomes, tubers, etc.) that are capable of
independent propagation of a new individual.
Plant Resources. Physical resources that can limit
plant growth, primarily including sunlight, water,
and mineral nutrients.
Weed. To qualify as a weed, a plant only needs to
be considered out of place or otherwise unwanted
where it is currently growing. In wildland settings
the term weed is not sufficient and a more specific
definition is required.
A prescribed burn at Chesapeake Marshlands National Wildlife Refuge Complex. Photo by Gerald Vickers,
USFWS.
7
Plant invasions can occur for several reasons. The
type of habitat disturbance, proximity to previously
invaded sites, the number and means available to
spread propagules, altered resource levels, and
disruption of ecological processes have all been
associated with invasive plants spreading into new
areas. All of these factors can be broadly lumped
into two primary variables (See Figure 1):
1. the availability of plant propagules; and
2. the availability of plant resources.
Plant Propagules
When considering plant propagule availability, it is
important to consider the species they represent in
addition to their abundance. If numerous propagules
reach an area, but their specific characteristics are
not adapted to the local environment, they are not
likely to establish a population. Even if propagules
are well suited for establishing and reproducing in
a new environment, they still may not establish a
population if the initial number of propagules is too
small.
In contrast, if many propagules disperse that
are compatible in a new environment, then a new
population is likely to establish. Propagules can
be introduced deliberately (i.e., added to postfire
seeding mixes) or accidentally (i.e., contaminant
species in postfire seeding mixes or straw mulch)
(Fig. 2, link A). Plant propagule numbers can be
reduced by seed predators (i.e., mice, squirrels, and
many birds) or diseases that reduce the reproductive
rates of invasive plants. Established invasive
populations can spread locally, creating a feedback
loop that can become problematic (Fig. 2, link C).
Section III
How Do Plant Invasions Occur?
Plant Propagules
Plant Resources
(includes water, sunlight, and mineral nutrients)
high
invasion
potential
low
invasion
potential
Invasion Potential
Plant Propagules
(number of seeds and other plant parts capable of
reproducing available to establish or increase a population)
Plant Resources
Management Strategy
reduce
resource
availability
reduce
propagule
availability
Figure 1. Main factors affecting plant invasions (adapted from Brooks 2007)
A Recipe for Trouble
Invasive potential is highest when propagules of invasive plants are likely to reach new areas
that offer the combination of resources (soil nutrients, sunlight and moisture) necessary to
establish and compete with native plants for these resources.
8
Resource Availability
In vegetation types where there is frequent natural
disturbance, native vegetation is often able to
recover quickly (i.e., by resprouting or establishing
from seed), and therefore high resource availability
following disturbance may not be a factor in invasive
plant populations becoming established.
In other vegetation types, plant resource availability,
particularly soil nutrients, can affect whether
invasive plants become established. Following a
fire, such resources can be increased directly, (i.e.,
postfire fertilization) or indirectly from the sudden
reduced competition for nutrients after vegetation is
removed (Fig. 2, link B).
Established populations of invasive plants can affect
the supply of resources available (Fig. 2, link D).
For example, some invasive plants might limit the
growth of other species through competition or
inhibition of nutrient uptake.
Processes that reduce plant resource availability,
such as postfire recovery of vegetation, can reduce
invasion potential. As vegetation recovers, resource
uptake increases.
Invasive Species
Abundance
Plant Propagules
Deliberate
Dispersal
Accidental
Dispersal
Plant Resources
Increasing
Input
Decreasing
Uptake
A B
C D
Figure 2. Relationships between propagule availability, resource availability, and invasive
species abundance (adapted from Brooks 2007). Plant propagules (A) and plant resources
(B) both affect the abundance of nonnative plant populations. Once these populations are
established, they can affect plant propagules (C) and plant resources (D).
Regrowth of grass postfire. Photo by M.
Weisenberger, USFWS
Golden crownbeard (Verbesina encelioides) regrowth
following a prescribed burn in pinyon-juniper
habitat. Photo by M. Weisenberger, USFWS.
9
There are three general reasons why management
of invasive plants should be combined with the
management of fires:
1) Fires can promote plant invasions.
2) Fire can be used as a tool to control plant
invasions.
3) Plant invasions can affect fuels, fire behavior,
and fire regimes.
1. Fires Can Promote Plant Invasions
Fires can quickly and dramatically change the
landscape and alter the competitive balance within
the biotic community. Fires consume plant biomass,
which increases the availability of light and reduces
the consumption of soil nutrients, thus increasing
invasion potential during at least the first few
postfire years (Fig. 2).
Most invasions by nonnative plants that have been
reported in the scientific literature report situations
where invasive plants were already established
within landscapes prior to fire. However, disturbance
as a result of a fire event served as an opportunity
for invasive plants to expand their local distributions
and dominance.
Although fire may not be necessary for an invasive
plant to become established in an area, it may allow
the population to expand to the point that it harms
the local ecosystem. From an ecological standpoint
and from the perspective of land managers, such
negative effects represent the area of greatest
concern, and may require a response.
In some native vegetation types that are fire
dependent (i.e., chaparral), increased dominance of
invasive plants may be fleeting; native vegetation
quickly recovers and outcompetes invasive plants.
Where native vegetation is not dependent on fire,
however, the plants do not respond fast enough,
allowing invasive plants to establish and spread
(i.e., some desert shrublands).
Thus, the effects of fire on the spread of invasive
populations can depend on the biology of the native
vegetation, such as the rate at which it recovers
following fire.
Section IV
Why Should the Management
of Invasive Plants and Fires Be
Combined?
Burning piles of Russian thistle (Salsola spp.) to control seed dispersal. Photo by M. Weisenberger, USFWS.
10
2. Fire Can be Used to Control Plant Invasions
Fire has been used since pre-historic times to
manage vegetation for various purposes. Modern
use of fire in wildland areas has focused on
treatments to reduce hazardous fuel loads, restore
historical disturbance regimes, improve forage and
habitat for game and livestock, promote biodiversity,
and manage nonnative invasive plants. Much of
what is currently known about using fire to control
invasive plants has been derived from studies of
cropland systems. Unfortunately, there are many
fundamental differences between cropland and
wildland settings, and our ability to use information
derived from croplands to predict effects that may
occur in wildlands is limited.
Fire has been used effectively to control invasive
late season annual broadleaf and grass species,
particularly yellow starthistle (Centaurea
solstitialis), medusahead (Taeniatherum caput-medusae),
barbed goatgrass (Aegilops triunciallis),
and some brome grasses (Bromus spp.). A limited
number of invasive biennial broadleaves [i.e.,
sweetclover (Melitotus spp.) and garlic mustard
(Alliaria petiolata)], perennial grasses [i.e.,
bluegrasses (Poa spp.) and smooth brome (Bromus
inermis)], and woody species [i.e., brooms (Cytisus
spp.) and Chinese tallow (Triadica sebifera)] have
also been successfully controlled with fire. The most
success comes when fire is integrated with other
control strategies (i.e., herbicides, mechanical)
within an integrated pest management framework.
Most scientific studies have focused on the responses
of specific invasive plants and largely disregard how
other species or the plant community responds as a
whole. This lack of information is a major problem
for land managers because the ultimate reason for
controlling invasives in the first place is to reduce
the dominance of the invasive species and increase
the dominance of the desired native species. Other
objectives may include increasing the status and/
or health of endangered plants, wildlife and insect
populations, and hydrologic function. If these results
are not achieved, then using fire to control target
invasive plant infestations may not be worth the
effort.
Land managers considering using fire to control
invasive plants should be careful to examine the
characteristics of the target invasive species. The
survival rate of plants depends on the degree to
which reproductive tissues are protected from
a fire’s lethally high temperatures. Plants with
reproductive tissues located below ground (i.e.,
seeds or tubers) have higher survival rates and tend
to recover more quickly than plants with vegetative
tissues located above ground (i.e., many shrubs and
trees) (Table 1).
Exposure of regenerative tissue
to damage from fire
Depends on if seeds are
located above-ground on the
parent plant, or at or below
the soil surface after they have
dispersed from the parent plant.
Protected from fire due to soil
insulation above them.
Depends on the percentage of
litter burned and the amount of
smoldering combustion.
Non-fire-adapted shrubs can
be killed by fire due to their
positioning directly in the flame
zone of surface fires.
Can be killed by crown fire
that passes though the plant
canopies, or by surface fire that
girdles the trees.
Life Form (Raunkiaer type)
Annual plants
Bulbs or corms
Rhizomatous plants
Shrubs
Trees
Regenerative tissue
Seeds that reside on or under
the soil surface, or on dead
plants
Living tissue well below the soil
surface
Living tissue just above or
below the soil surface
Living tissue just above the soil
surface
Living tissue well above the soil
surface
Table 1. Effects of fire on different plant life forms (modified from Pyke et al. in prep).
11
3. Plant Invasions Can Affect Fuels, Fire Behavior,
and Fire Regimes
One significant way that invasive plants can affect
the areas they are invading is by changing fuel
properties, which then affects fire behavior (Table
2). If the altered fuel properties remain or increase
after burning, then the fire regimes may be altered.
When altered fire regimes promote the spread of the
invaders that cause the changes in the first place,
then the system is considered to be in an invasive
plant / fire regime cycle.
There are four phases that lead to the establishment
of an invasive plant/fire regime cycle:
Phase 1 involves the initial spread of invasive plants
into an area.
Phase 2 is characterized by establishment of self-perpetuating
populations of the invasive plant.
Phase 3 occurs when the plant spreads beyond the
area first infested, especially disturbed sites into less
disturbed wildland sites, and begins to negatively
impact surrounding native plant communities.
Phase 4 results in fuel properties being changed to
the point that the natural fire regime shifts. If the
new fire regime favors the spread of the invasive
species and reduces the native species, an invasive
plant/fire regime cycle becomes established (Fig. 3).
The most well-known effects of plant invasions
on fire regimes involve those that increase the
frequency, intensity, or length of the fire season.
Collectively, these changes increase what are
commonly referred to as “fire hazards.” For
example, annuals grasses that have invaded
shrublands can increase the frequency of fire and
the length of the fire season in the western United
States, and invaders that increase the woody fuel
load can increase fire intensity in the southeastern
United States. In addition, invading plants with
high tissue flammability (i.e., Eucalyptus) can ignite
easier and burn more intensely.
Plant invasions don’t always increase fire hazards,
and in some cases can actually reduce them.
Invasions can make fuelbeds less flammable
by increasing live fuel moisture, decreasing
fuel continuity, or decreasing fuel loads (Table
2). Examples are harder to find because managers
are generally less concerned about decreased
fire hazards than they are about increased fire
hazards. Potential examples include succulents (i.e.,
cactus and iceplant spp.) invading shrublands and
increasing live fuel moisture, or trees that shade
out surface vegetation and reduce surface fuel
continuity.
Table 2. Primary effects of fuelbed changes on fire regimes.*
Fuelbed Change Fire Regime Change
Increased amount (load) Increased fire intensity and seasonal
burn window; increased likelihood of crown fire
Decreased amount (load) Decreased fire intensity and seasonal
burn window; decreased likelihood of crown fire
Increased horizontal continuity Increased fire frequency and extent
Decreased horizontal continuity Decreased fire frequency and extent
Increased vertical continuity Increased likelihood of crown fire
Decreased vertical continuity Decreased likelihood of crown fire
Change in packing ratio Change in fire frequency, intensity, and
seasonality
Increased plant tissue flammability Increased fire frequency, intensity, and
seasonal burn window
Decreased plant tissue flammability Decreased fire frequency, intensity, and
seasonal burn window
* Modified from Brooks et al. (2004) Table 1
12
As fire regimes and other ecosystem properties
become altered, restoration of pre-invasion
conditions becomes increasingly more difficult and
costly. As the invasive plant infestation spreads and
alters the fire regime, the number of management
actions and cost to restore native ecosystem
functions increases, while the probability of success
decreases. This is because restoration can ultimately
require managing fuel conditions, fire regimes,
native plant communities and other ecosystem
properties, in addition to the invaders that caused
the changes in the first place.
As with other ecological impacts caused by plant
invasions, the most cost effective way to prevent the
establishment of an invasive plant / fire regime cycle
is to take preventative steps early on in the process.
Figure 3. The Invasive Plant/Fire Regime Cycle. Modified from Brooks, et al. (2004).
+ Fire Regime
Fuels
-
Nonnative Plants Nonnative Plants
-
Prescribed burn on Buffelgrass (Pennisetum ciliare) on the Lower Rio Grande NWR. Photo by South Texas
Fire District, USFWS.
13
General guidelines have recently been published
for reducing the spread and dominance of invasive
plants in postfire landscapes (Asher et al. 2001,
Goodwin et al. 2002, Keeley 2003). Collectively
these publications present the following general
recommendations: 1) in response to individual
fires, procedures should be implemented to reduce
inadvertent dispersal of weeds into or within the
burned area; 2) areas where invasive plants of
particular concern are likely to invade or increase in
dominance should be targeted for control efforts;
3) additional revegetation treatments of other
species may be effective at competing with the
target invasives by reducing resource availability;
and 4) National Environmental Policy Act (NEPA)
analyses that are likely to be required prior to
implementing postfire control treatments (i.e.,
herbicide use) should be completed and ready to use
before the fire season. A Pesticide Use Plan (PUP) is
also required before herbicides can be approved for
use.
Although these existing guidelines are helpful, they
are basically checklists of do’s and don’ts, and there
is always the chance that situations may arise where
appropriate guidance is not found on one of the lists.
For example, these guidelines generally focus on fire
suppression and postfire emergency stabilization,
rehabilitation, and restoration activities, and do not
address issues associated with fuels management.
They also do not explicitly integrate fire
management with other land management programs
during the years leading up to and following fires,
nor do they provide specific guidance on prioritizing
which actions may be most effective
in a given situation.
The approach of this handbook is to explain the
primary mechanisms associated with plant invasions
(i.e., resource availability and propagule availability),
and provide examples of how their effects can be
mitigated to minimize invasion potential. With
a basic working understanding of the invasion
Section V
General Operational Guidelines
for Fire Management
Prescribed fire for standing-dead salt cedar. Photo by M. Weisenberger, USFWS.
14
process, a land manager can then better evaluate
how best to integrate fire management actions
(preparedness, suppression, wildland fire use,
prescribed fire, hazardous fuels and post-wildfire
recovery treatments,) into overall land management,
especially when they encounter situations that
are not described in existing guidelines. This
knowledge will also help land managers prioritize
the prevention steps that are most important for
reducing invasion potential in their particular
situation. Examples are provided below that focus
on minimizing plant propagules and resource
availability, using the conceptual model presented
earlier in this document (Figs. 1 and 2). In later
sections the conceptual model is applied to managing
invasive plants in the context of specific fire
management activities.
Minimizing Propagule Availability
Propagule availability can be reduced by ensuring
that seeding treatments do not include species that
may become management problems in the future
(Table 3). Careful consideration of all the problems
associated with introductions of both nonnative
plants, and native species outside of their native
ranges, is the easiest way to reduce invasive species.
Regional lists of invasive plants can be consulted to
help inform fire managers of plants to avoid.
A much greater challenge involves managing
propagule availability due to accidental dispersal of
invasive plants from outside of a management unit
(Table 3). This includes both long-distance dispersal
from outside of the management unit and short-distance
dispersal from adjacent areas, some of
which may lie within the management unit. Sources
of long-distance dispersal include vehicles and other
mechanized equipment, personal items (clothes,
boots, camping equipment), livestock from distant
locations, seed mixes or other vegetation stock, and
erosion control materials from distant locations (i.e.,
soils, rock, hay mulch). These sources are connected
primarily to human transportation, so control can
be focused where they enter the management unit
of interest (i.e., fire camps, erosion control project
areas). Short-distance dispersal from adjacent areas
is much more difficult to manage than long-distance
dispersal, because sources and pathways include all
of the above plus mechanisms such as wind, water,
wildlife, human foot traffic, and other localized
human activities.
The challenge in managing invasions that arise from
outside of a management unit is in detecting and
eradicating the new invaders before they establish
local populations. Necessary steps to detect and
eradicate these new invaders include reducing
dispersal rates, detecting newly established
individuals, and eradicating them. Each of these
steps is potentially very costly, so land managers
need to evaluate how to get the most “bang for the
buck.”
Minimizing Resource Availability
One of the most obvious recommendations for
reducing the likelihood an area will be invaded is
to reduce resource inputs such as adding nitrogen
or phosphorous to the soil (Table 3). Second only
to soil moisture, these nutrients are often the
primary limiting factors of plant growth. It may
seem like a good idea to add these nutrients to give
native vegetation some help as they recover from
a fire event, but unfortunately invasive plants can
often take advantage of large increases in nutrient
availability more effectively than native plants.
Increased invasive plant biomass fueled by nutrient
additions creates additional water demands, and
can lead to increased competition for soil moisture.
For similar reasons, the use of nitrogen-fixing plants
which can increase available soil nitrogen should be
used with caution in revegetation treatments.
Resource availability can also be reduced by
maximizing resource uptake (Table 3). This can
be done by retaining existing vegetation as much
as possible in fuels treatments. For example, if
hazard fuels reduction can be achieved by only
removing ladder fuels, while retaining surface and
canopy fuels, then the potential for subsequent
plant invasion should be lower than if surface
fuels or surface and canopy fuels are removed as
well. Resource uptake can also be accomplished
by adding vegetation in postfire emergency
rehabilitation projects. Carbon sources, such as
organic mulches, can help reduce levels of available
nitrogen.
15
Minimize accidental dispersal
Decontaminate equipment by washing after
use and/or before using at a new geographic
location.
Implement an early detection and rapid
response plan during the first 3 years following
fire to detect and eradicate new populations of
invasive plants within the management unit.
Implement a control and monitoring plan during
the first 3 years following fire to keep existing
invasive plant populations from spreading within
the management unit.
Maximize resource uptake
Reduce loss of vegetation biomass
Promote the re-establishment of desirable
vegetation, either through direct seeding,
planting or implementation of appropriate land-use
regimes (i.e., temporary closures to grazing)
Use carbon sources (i.e., organic mulches) to
reduce available soil nitrogen.
Prevent deliberate dispersal
Carefully evaluate plants considered for
use in revegetation projects to ensure that
they are unlikely to become management
problems in the future.
Minimize resource input
Avoid using nitrogen or phosphorous soil
amendments
Avoid revegetating with nitrogen-fixing
plants (i.e., legumes)
Table 3. General recommendations for minimizing the potential for plant invasions following fire
and fire management actions.
Plant Propagules
Plant Resources
16
Fuels Management
Fuel management practices can also lead to the
proliferation of invasive plants. Fuels management
almost universally involves removal of plant
biomass, which has the potential to increase nutrient
availability and thus increase the likelihood an area
will be invaded. Crews and equipment used for fuels
treatments also have the potential to spread invasive
plants. The window of opportunity for invasions
largely depends on how long it takes for native
vegetation to recover compared to the time invasive
plants become established and spread.
Once established, invasive plants can create new
and unexpected fire hazards that may be even more
difficult to manage. Even fuel treatment specifically
targeted to remove an invasive plant [e.g., salt cedar
(Tamarix spp), or giant reed (Arundo donax)] can
be followed by invasion of another species that, in
turn, could bring additional problems. Monitoring
for new invasive plants following the fuels
treatments may be necessary.
Recommendations for lessening the possibility that
a fuels management treatment may increase the
spread of invasive plants apply to the degree that
project goals can still be achieved (i.e., establishment
of a managed fuel zone). Evaluating what is required
to achieve fuels management goals requires analyses
beyond the scope of this handbook (i.e., fire behavior
modeling).
Plant propagules
If the locations of invasive plants are known prior
to planning a fuel treatment then those locations
can be avoided when possible. The effect of fuels
treatments on nutrient availability may be tempered
by whether or not potentially invasive plants are
nearby. For example, invasive plants may spread
after a fuel treatment where past disturbances left a
large number of invasives, but not where there were
few invasives prior to the treatment.
Unfortunately, invasive plants are often associated
with roads and trails which are commonly used as
anchor points for fuels treatments.
Section VI
Specific Operational Guidelines
for Major Fire Management
Activities
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into the project
site.
Avoid incorporating pre-existing invasive plant
populations into managed fuel zones.
Implement a monitoring and control plan for
invasive plants after the fuels treatments are
applied.
Identify populations of invasive plants within the
project area and focus control efforts in those
areas.
Reducing Resource Availability
Minimize vegetation removal while still
accomplishing fuels management objectives.
Target only the fuel layers that typically
carry fire (i.e., the understory and ladder
fuels in a forest).
Selectively thin to reduce fuel continuity
rather than clear-cut.
Construct fuel breaks no wider than
necessary to accomplish fuel reduction
objectives.
Consider revegetating with less flammable
vegetation following removal of flammable
vegetation.
Cover exposed soil with an organic mulch (i.e.,
hydromulch or chipped fuels).
Incorporate pre-existing fuel breaks, either man-made
or natural (i.e., areas of bare rock), into
managed fuel zones.
Fuels Management Treatments
Best management practices for minimizing the potential for plant invasions
17
Plant resources
Fuels treatments can involve the complete or
partial removal of plant biomass. The greater the
percentage of existing vegetation that is removed,
the greater the potential for spread of invasive
plants. For example, cover of invasive plants
often increases with the proportion of overstory
vegetation that is removed. Also, treatments that
involve both fuels thinning and burning can lead to
higher invasive plant cover than treatments that
include one or the other individually.
In some cases fuels management may include adding
plant cover of low flammability, commonly called
greenstripping. This technique involves the strategic
planting of low flammability plants to prevent or
reduce the rate of fire spread. It has been used
effectively by the Bureau of Land Management
in the Intermountain West. An added benefit of
greenstripping is its potential to reduce nutrient
availability for invasive plants such as cheatgrass
(Bromus tectorum). However, the benefits of adding
potentially aggressive greenstripping plants (which
are typically nonnative) to reduce fire spread and
compete with other undesirable species such as
cheatgrass (Bromus tectorum) must always be
weighed against the potential negative effects
of the species (i.e., competition with natives or
other ecosystem impacts). More information on
greenstripping can be found at http://fresc.usgs.gov/
research.
Fire Suppression
Over time, invasive plants can pose even greater
management challenges than the fires themselves.
The recommendations below are designed to reduce
the likelihood for fire suppression activities to
create opportunities for invasive plants to become
established. These recommendations should only
be considered when there is no immediate threat to
human life and/or property.
Plant propagules
Fire suppression activities are more likely to
influence propagule availability than resource
availability. Fire-fighting crews and their equipment
can move invasive plants as they travel. Firefighters
set up small camps and their equipment largely
consists of personal belongings (i.e., boots, clothes,
sleeping bag, tent), Personal Protective Equipment
(PPE)(i.e., nomex gloves, helmet, goggles, fire pack,
fire shelter), back-pack sprayers, and hand tools
(i.e., shovels, pulaskies, axes, fire rakes, hoes). This
equipment can help spread invasive plants unless
they are cleaned prior to use at other locations. At
the very least, fire-fighters should clean tools, boots,
and tents prior to arriving and leaving a fire site.
Heavy equipment such as bulldozers probably
have the greatest potential for spreading invasives
because they often accumulate significant amounts
of soil and vegetation debris in their undercarriages.
When heavy equipment is used, it should either be
washed prior to transport or washed before it is
allowed to operate in new wildland areas.
Care is taken to limit burning near roads where no invasive plants are present. Photo by M. Weisenberger,
USFWS.
18
Aircraft are often used to transport and disperse
water, foam, or other fire retardant. These aircraft
may be helicopters with buckets, or fixed-wing
aircraft known as tankers or scoopers. There is
some concern that helicopters or scoopers could
carry invasive plants in the water they use. Aquatic
or riparian plants are most likely to be transported
in this manner, and because they are most likely
to be deposited into upland sites where most fires
occur, they would likely not become established.
A significant exception may be the potential for
establishment in springs and creeks that are often
common in upland areas. In general, the likelihood of
moving invasive plants long distances by this method
is probably low because water is typically obtained
from local sources near fires.
Plant resources
Fire suppression activities rarely lead to increased
resource availability, although there are a few
notable exceptions. For example, the use of
phosphate-based fire retardants may lead to
increased growth of invasive plants where phosphate
is a limiting nutrient. The construction of fuelbreaks
and some firelines, both by handcrews and by
heavy equipment, could lead to increased nutrient
availability due to reduced rates of consumption
from plants that are removed to clear the line.
Backing fires could have similar results for the same
reasons. More temporary control lines such as wet
lines or foam lines may be less likely to encourage
plant invasions because the existing vegetation is left
in place.
Emergency Stabilization, Rehabilitation, and
Restoration
Plant propagules
Seed mixes and application equipment are potential
sources for invasive plants. Seed mixes should be
inspected to ensure they are “weed free.” This
may require testing sub-samples to determine
their species composition before they are applied.
Application equipment also needs to be cleaned
before and after use, especially if equipment was
previously used in areas with known invasive plant
infestations.
Plant resources
Plants are mostly seeded after fires to stabilize
soils, but in some cases they are seeded to compete
with and suppress invasive plants. For example,
nonnative wheatgrasses (Agropyron spp.) have often
been planted to suppress the growth of cheatgrass in
the Intermountain West.
Jeff Olson at the Prescribed Fire Training Center. Photo by Greg Zoppetti, USFWS.
19
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into burned areas.
Coordinate with local personnel who know the
locations of invasive plants or who can quickly
survey sites for their presence.
Include warnings to avoid known areas infested
with invasive plants during briefings at the
beginning of each shift.
Avoid establishing staging areas (i.e., fire
camps, helibases) in areas dominated by
invasive plants.
If populations of invasive plants occur within
or near staging areas, flag their perimeters so
that vehicle and foot traffic can avoid them.
Inspect vehicles and equipment and wash them
if they have invasive plants or materials that
may contain invasive plants (i.e., mud) on them.
Inspections should be done when vehicles first
arrive at the fire, and periodically during the
fire as they return from working in the field.
Avoid the use of water from impoundments
infested with invasive plants.
Identify populations of invasive plants within the
burned area and focus postfire control efforts in
those areas.
For pre-planned wildland fire, environmental
assessments should at least document the
locations of major populations of invasive plants
within the proposed burn unit and evaluate the
potential for the burn prescription to increase
their dominance and spread. If the potential is
high, either remove those areas from the burn
unit or develop a postfire mitigation plan.
Implement a postfire monitoring and control
plan for invasive plants. Focus on populations of
invasive plants known to exist before the fire and
on areas of significant fire management activity
during the fire (i.e., fire camps, dozer lines).
Reducing Resource Availability
Minimize vegetation removal in the construction
of control lines.
Use wet lines and foam lines as much as
possible.
Use narrow handlines rather than broad dozer
lines or blacklines.
Minimize the use of nitrogen and phosphate-based
retardants, except where their use
eliminates the need for vegetation removal.
Tie control lines into pre-existing fuel breaks and
managed fuel zones.
During mop up, scatter organic matter back over
exposed soil where control lines were established.
Fire Suppression
Best management practices for minimizing the potential for plant invasions
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel do
not spread invasive plants into the project site.
Revegetate with native species, or nonnatives that
are not likely to become invasive.
Test seed mixes or other types of revegetation
materials to ensure that they do not contain
invasive plants as contaminants.
Implement a monitoring and re-treatment plan
for invasive plants after the initial treatments are
applied.
Reducing Resource Availability
Vegetate with fast-growing but non-invasive plants
to increase the uptake of resources that would
otherwise be utilized by invasive plants.
Cover exposed soil with an organic mulch (i.e.,
hydromulch or chipped fuels).
Focus efforts on reducing resource availability in
areas with sources of invasive plants.
Emergency Stabilization, Rehabilitation, and Restoration
Best management practices for minimizing the potential for plant invasions
20
Postfire Land-Use Regimes
Plant propagules
Any land-use activity increases the chance for
accidental introduction of invasive plant, so
reducing these activities can lessen the potential
for plant invasions. Invasive plants can be moved
by many ways, including people, stock animals,
pets, vehicles, equipment, and livestock feed just to
name a few. Thus, any person or anything traveling
into a recently burned area should be considered
a potential vector. It is much more cost effective to
prevent plant invasions than to manage them after
invasive plant populations are firmly established.
Plant resources
There are often significant demands to quickly
re-establish prevailing land-use activities following
fires. If these activities affect resource availability,
they may increase the likelihood an area will be
infested by invasive plants. For example, livestock
grazing is a common land-use on public lands,
and one of its main effects is the removal of plant
biomass. Biomass removal generally reduces levels
of competition and increases the availability of soil
nutrients, thus increasing the potential for invasive
plants to move into an area.
If it is possible to target grazing on invasive plants,
then it may help counteract the effects of increased
soil nutrients. However, the ability to control
what livestock eat makes focusing on undesirable
vegetation very difficult. In addition, repeated
grazing in focused areas over longer periods of
time can lead to other problems such as soil erosion
and loss of native species diversity, and even short
periods of deferred grazing may allow nonnatives to
rise to dominance.
Postfire Land-Use Regimes
Best management practices for minimizing the potential for plant invasions
Reducing Propagule Availability
Ensure that vehicles, equipment, and personnel
do not spread invasive plants into burned areas.
Consider temporary closure of public access to
burned areas to of invasive plants.
Consider using livestock grazing to target
invasive plants for short-term control.
Reducing Resource Availability
Minimize land uses that may reduce vigor of
resprouting of native plants (i.e., livestock
grazing).
Treating invasive plants with fire. Photo by M. Weisenberger, USFWS
21
Monitoring management actions should focus on
responses of immediate interest, but should also
consider abiotic factors. In most cases, monitoring
is associated with the management action of interest
(i.e., the influence of fuels management on fuel
characteristics). Monitored responses will sometimes
extend to secondary effects (i.e., the influence of
fuels management on fuel characteristics, and
ultimately on fire behavior and fire regimes). At a
minimum, monitoring needs to determine whether
objectives of the management action have been
achieved.
Commonly used agency monitoring publications,
described in Table 4, outline vegetation monitoring
methodology, although none specifically address
invasive plants. Monitoring plans should include
the following elements: objectives, stratification,
controls, random sampling, data quality, and
statistical analysis. All of these topics, except for
controls, are discussed at length in the publications
listed in Table 4; only two monitoring publications
(USDI National Park Service 2003, Lutes et al. 2006)
cover all six monitoring elements.
Section VII
Effectiveness Monitoring
Table 4. Agency publications on monitoring.
Monitoring Publication Covers Fire Monitoring Associated Software
Fish and Wildlife Service
Fuel and Fire Effects Monitoring Guide Yes No
(USDI Fish and Wildlife Service 1999)
Bureau of Land Management No No
Sampling Vegetation Attributes
(Interagency Technical Reference 1999)
National Park Service
Fire Monitoring Handbook Yes Yes
(USDI National Park Service 2003)
Forest Service
FireMon: Fire Effects Monitoring and Yes Yes
Inventory Protocol (Lutes et al. 2006)
Agricultural Research Service
Monitoring Manual for Grassland, No Yes
Shrubland, and Savanna Ecosystems
(Herrick et al. 2005a,b)
22
Asher, J.E., S. Dewey, C. Johnson and J. Olivarez.
2001. Reducing the spread of invasive exotic
plants following fire in western forests, deserts,
and grasslands (abstract). In: Galley KEM and
Wilson TP (Eds) Proceedings of the Invasive
Species Workshop: the Role of Fire in the Control
and Spread of Invasive Species. Fire Conference
2000: the First National Congress on Fire
Ecology, Prevention, and Management, pp 102-
103. Tall Timbers Research Station, Tallahassee,
FL.
Brooks, M.L. C.M. D’Antonio, D.M. Richardson,
J. Grace, J. J. Keeley, DiTomaso, R. Hobbs, M.
Pellant, and D. Pyke. 2004. Effects of invasive
alien plants on fire regimes. BioScience 54:677-
688.
Brooks, M.L. 2007. Effects of land management
practices on plant invasions in wildland areas.
Pages 147-162 in: W. Nentwig (ed.) Biological
Invasions. Ecological Studies, Vol. 193, Springer,
Heidelberg, Germany.
Champion, P.D., and J.S. Clayton. 2001. A weed
risk assessment model for aquatic weeds in
New Zealand. Pages 194-202 in R.H. Groves,
F.D. Panetta, and J.G. Virtue (eds.), Weed risk
assessment. CSIRO, Collingwood, Victoria,
Australia.
D’Antonio, C.M. and P.M. Vitousek. 1992. Biological
invasions by exotic grasses, the grass/fire cycle,
and global change. Annual Review of Ecology and
Systematics. 23:63-87.
D’Antonio, C.M. 2000. Fire, plant invasions and
global changes. In: H. Mooney and R. Hobbs
(Eds). Invasive species in a changing world, pp.
65-94. Island Press, Covela.
DiTomaso, J.M., M.L. Brooks, E. B. Allen, R.
Minnich, P. M. Rice, and G. B. Kyser. 2006. Control
of invasive weeds with prescribed burning. Weed
Technology 20:535-548.
DiTomaso, J. M. and D. W. Johnson (Eds.). 2006.
The Use of Fire as a Tool for Controlling Invasive
Plants. Cal-IPC Publication 2006-01. California
Invasive Plant Council: Berkeley, CA. 56 pp.
Fox, A. M., D.R. Gordon, J.A. Dusky, L. Tyson,
and R.K. Stocker. 2001. IFAS assessment of
non-native plants in Florida’s natural areas.
SS-AGR-79. Agronomy Department, Florida
Cooperative Extension Service, Institute of
Food and Agricultural Sciences, University of
Florida. Available online at http://agronomy.ifas.
ufl.edu/docs/IFASAssessment2001.pdf
Galley, K. E. and Wilson. 2001. Proceedings of the
Invasive Species Workshop: The Role of Fire in
the Control and Spread of Invasive Species. Fire
Conference 2000: The first National Congress on
Fire Ecology, Prevention and Management, San
Diego, CA, Misc. Pub No. 11.
Godwin, K., R. Sheley, and J. Clark. 2002. Integrated
Noxious Weed Management After Wildfires.
Montana State University Extension Service. 26
pp. Available online at www.montana.edu/wwwpb/
pubs/eb160.html.
Heffernan, K.E., P.P. Coulling, J.F. Townsend,
and C.J. Hutto. 2001. Ranking invasive exotic
plant species in Virginia. Natural Heritage
Technical Report 01-13. Virginia Department of
Conservation and Recreation, Division of Natural
Heritage: Richmond, Virginia. 27 pages. Avalable
online at http://www.dcr.state.va.us/dnh/rankinv.
pdf
Herrick, J.E., J.W. Van Zee, K.M. Havstad, L.M.
Burkett, and W.G. Whitford. 2005a. Monitoring
Manual for Grassland, Shrubland, and Savanna
Ecosystems. Volume 1: quick start. USDA-ARS
Jornada Experimental Range. Las Cruces, NM.
36 p.
Herrick, J.E., J.W. Van Zee, K.M. Havstad, L.M.
Burkett, and W.G. Whitford. 2005b. Monitoring
Manual for Grassland, Shrubland, and Savanna
Ecosystems. Volume 2: design, supplementary
methods and interpretation. USDA-ARS Jornada
Experimental Range. Las Cruces, NM. 200 p.
Hiebert, R.D., and J. Stubbendieck. 1993. Handbook
for Ranking Exotic Plants for Management
and Control. U. S. Department of the Interior,
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Keeley, J.E. 2003. Fire and invasive plants in
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63:18-19
Klinger, R.E. Underwood, P. Moore. 2006. The role
of environmental gradients in non-native plant
invasion into burnt areas of Yosemite National
Park, California. Diversity and Distributions 12:
139-156.
Section VIII
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Towards a system to determine the national
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355 pp.
Using drip torches to apply fire to buffelgrass on the Lower Rio Grande Valley National Wildlife
Refuge. Photo by South Texas Fire District, USFWS.
24
Federal Mandates
The following is a chronological list of federal laws,
executive orders and management plans pertaining
to invasive plant control with fire management
activities on federal lands. Federal Acts may be
found on-line at: http://www.gpoaccess.gov/uscode/
search.html; or Public Laws (since 1994) at: http://
www.gpoaccess.gov/plaws/search.html.
National Wildlife Refuge System Administration
Act, as amended
This act establishes the Fish and Wildlife Refuge
System. This act requires the agency to administer
lands to provide for the conservation of fish,
wildlife, plants and their habitats and to ensure that
biological integrity and diversity are maintained.
National Environmental Policy Act (1970)
This act requires government agencies to consider
the environmental effects of their actions through
the preparation of appropriate NEPA documents
(i.e., EAS, EA or EIS). Effects of nonnative species,
if harmful to the environment, would be included
in NEPA analysis. In emergency situations, NEPA
procedures that would normally be required may
be negotiated with the Council of Environmental
Quality.
Endangered Species Act (1973)
This Act protects federally listed Threatened and
Endangered species. When nonnative invasive
species threaten a Threatened or Endangered
species, this Act could be used to justify treatment
of the infestation.
Federal Land Policy and Management Act (1976)
This act establishes public land policy and
guidelines for its administration and to provide for
the management, protection, development, and
enhancement of public lands.
Lacey Act (1981)
Under this Act it is unlawful to import, export,
transport, buy or sell fish, wildlife and plants taken
or possessed in violation of federal, state or tribal
laws.
Appendix A.
Laws, Policies And Planning Documents
Guiding the Management of Invasive
Plants and Fire
Using fire as a beneficial tool to treat invasive plants. Photo by M. Weisenberger, USFWS
25
Hawaii Tropical Forest Recovery Act (1992)
This Act establishes the Hawaii Tropical Forest
Recovery Task Force to draft a plan for rejuvenating
Hawaii’s tropical forests.
Executive Order 13112 (1999)
This Order defines invasive species as an alien
species whose introduction does or is likely to cause
economic or environmental harm or harm to human
health. It directs all federal agencies to address
invasive species concerns and refrain from actions
that are likely to increase invasive species problems.
This Order also established the National Invasive
Species Council and the development of a National
Invasive Species Management Plan to better
coordinate efforts among federal agencies.
Plant Protection Act (2000)
This Act replaced many previous invasive plant
species acts including the Federal Noxious Weed
Act, the Plant Quarantine Act, the Federal Plant
Pest Act and other related statutes and primarily
applies to USDA, but authorizes APHIS to take both
emergency and extraordinary actions to address
incursions of noxious weeds which can be regulated
on federal lands.
Noxious Weed Control and Eradication Act (2004)
This Act is an amendment to the Plant Protection
Act above and provides for the provision of
funds through grants and agreements to weed
management entities for the control and eradication
of noxious weeds.
National Invasive Species Council Management
Plan (2008)
The National Invasive Species Council was
established by Executive Order 13112. One of its
directives under the EO is to prepare a management
plan for invasive species that will provide guidance
for all federal agencies over a four year period.
Department of Interior Policy
The Departmental Manual (DM) has several policies
addressing invasive species management issues. The
following is numerically ordered list of DM policies
that relate directly or indirectly to fire and invasive
species management activities. DM policies may be
found on-line at: http://elips.doi.gov/app_dm/index.
cfm?fuseaction=home
516 DM 2 - Initiating the NEPA Process (2005)
This purpose of this Chapter is to provide
instructions for implementing CEQ regulations that
pertain to initiating the NEPA process. Appendix
2.12. states that the introduction of invasive species
is an extraordinary circumstance to a Categorical
Exclusion according to the Federal Noxious Weed
Control Act and Executive Order 13112.
Appendix 1 provides a list of management actions
that are DOI Categorical Exclusions pursuant
to 516 DM 2.3(A). Included in these actions
are: 1.6 - non-destructive inventory, research
and monitoring activities, 1.12 - Hazardous
fuels reduction activities using prescribed fire
not to exceed 4,500 acres, and 1.13 - Post-fire
rehabilitation activities not to exceed 4,200 acres.
Appendix 2 lists Extraordinary Circumstances
for some actions covered under Categorical
Exclusions. Relevant actions include: 2.3 - Have
highly controversial environmental effects, 2.4 -
Involve unknown environmental risks, and 2.12
- Contribute to the introduction or spread of non-native
invasive species.
516 DM 8 - Managing the NEPA Process -
U.S. Fish and Wildlife Service (2004)
This Chapter provides supplementary requirements
for implementing provisions of 516 DM 1 through
6 within the Department’s U.S. Fish and Wildlife
Service. Section 8.5 lists important Categorical
Exclusions for FWS activities. Relevant Categorical
Exclusions that may cover some fire and invasives
management actions include:
8.5.B(1): Research, inventory, and information
collection activities.
8.5.B(3): The construction... structures and
improvements for the restoration of wetland,
riparian, instream, or native habitats, which result
in no or only minor changes in the use of the
affected local area.
8.5B(4): The use of prescribed burning for habitat
improvement purposes.
8.5B(5): Fire management activities, including
prevention and restoration measures.
8.5B(6): The reintroduction or supplementation
(e.g., stocking) of native, formerly native, or
established species into suitable habitat within
their historic or established range.
517 DM 1 Integrated Pest Management Policy
(2007)
This policy updates the Integrated Pest
Management (IPM) policy to make it consistent
with current laws, contemporary science, and other
authorities. The revised policy addresses the IPM
process and pest management tools, including
pesticides and biological control agents.
522 DM Implementation of Adaptive
Management Policy (2008)
This Chapter provides guidance to help Agencies
incorporate adaptive management strategies
into their land and resource management
decisions. Section 1.5 (B) requires offices to conduct
appropriate monitoring to determine resource status
and evaluate progress toward achieving objectives.
606 DM 2 Soil and Moisture Conservation Policy
(1971)
This policy affirms that the purpose of the soil
conservation program is to restore and maintain
soil properties for optimal conditions. Both burning
26
and weed control are listed as an appropriate
soil and moisture conservation activities for site
improvement (Section 2.2.B.1).
609 DM 1 Weed Control Program Policy (1995)
This policy defines undesirable plants/weeds as
noxious when they interfere with man’s activities
or welfare. It is DOI policy to control undesirable
plants on lands under its jurisdiction. Further,
programs within DOI for the control of undesirable
plants will incorporate integrated pest management
practices. DOI Bureaus will coordinate their
integrated pest management activities with other
federal and non-federal agencies where possible.
At the Bureau level, each Bureau is responsible for
planning, funding, implementing, and overseeing
integrated pest management programs. This policy
establishes the DOI weed control committee with
representatives from each bureau and is charged
with overall interdisciplinary program development.
620 DM 2 Burned Area Rehabilitation Policy
(2004)
This chapter provides the Departmental Policy for
the Emergency Stabilization and Rehabilitation
on Bureau lands and Indian Trust Lands following
wildland fires. Specifically, Section 3.8E states that
exotic species introductions as a part of seeding in
burned areas are restricted with exceptions from
the Secretary of the Interior. Section 3.2.W. states
that Executive Order 13112 is an authority for
conducting BAER activities. Other references to the
prevention of invasive species are found throughout
this Chapter.
Fish and Wildlife Service Policy
There are many citations throughout the Fish and
Wildlife Service Manual (FW), Administrative
Manual (AM) and Refuge Manual (RM) that
describe FWS policy as it relates to invasive species.
The following is a list of FWS and NWRS policies
directly or indirectly related to invasive species and
fire management activities. FWS policies may be
found on-line at: http://www.fws.gov/policy/manuals/.
Environment 30 AM 12 Pest Management Policy
and Responsibilities
This policy affirms that the FWS will use
integrated pest management in its planning of pest
management actions. Section 12.5 (B) lists burning
as a type of cultural control that can be used to
reduce pest populations.
052 FW 4 Planning and Management
This policy states that the ecosystem approach
concept to fish and wildlife management will be
implemented. Section 1.8.B.2.a.vii. states that
goals should include exotic species concepts when
developing plans.
Fire can be an effective tool to restore habitat on a landscape scale. Photo by M. Weisenberger, USFWS.
27
095 FW 3 Emergency Operations
This policy involves fire management activities.
Section 3.9.C.1.a. describes fire damage restoration
to include the use of herbicides, and other site
preparation activities to reduce weed competition
prior to seeding burned areas for restoration.
Section 3.9.B.2.E states that the FWS will minimize
the establishment of nonnative species in BAER
activities to prevent unacceptable degradation
to burned areas, Section 3.D.1.C. states that
fuels management projects will minimize the
establishment of invasive species.
601 FW 1 National Wildlife Refuge System
Mission and Goals and Refuge Purposes
This policy reiterates that the overarching goal of
the NWRS is to conserve a diversity of fish, wildlife,
and plants and their habitats by focusing on native
species.
601 FW 3 Biological Integrity, Diversity and
Environmental Health
This policy involves maintaining and restoring the
biological integrity, diversity and environmental
health of NWRs. Section 3.10.B3 states that the
FWS strives to minimize the spread of invasive
species; Section 3.11.B. states that the FWS should
use physical structures and chemical applications
to manage for biological diversity and eliminate
invasive species; Section 3.14.F. states that the
FWS supports the reintroduction of extirpated
native species to control invasive species if needed;
Section 3.16.A. states invasive species should not
be introduced, populations should be detected and
controlled through integrated pest management
strategies including mechanical, chemical, biological,
and cultural control methods.
602 FW 3 Exhibit 2 Comprehensive Conservation
Planning
This exhibit describes the statutes that should be
considered in the CCP process and identifies the
Noxious Weed Act as a mandate.
603 FW 1 Appropriate Refuge Uses
This policy states that invasive species control is
an accepted refuge management activity that is
included in appropriate refuge uses (Section 1.2.B).
603 FW 2 Compatibility
This policy states that refuge management activity
such as invasive species control does not require a
compatibility determination (Section 2.10.A).
620 FW 1 Habitat Management Plans
This policy describes guiding principles for the
development of habitat management plans on
refuges. Section 1.4.E defines the term invasive
species for habitat management plans; Section 1.7G
describes guiding principles which should include
invasive species management. Section 1.7.G. also
states that an integrated pest management plan will
be used to describe activities related to the control of
invasive species
640 FW 1 Partners for Fish and Wildlife Program
This chapter describes the implementation of the
Partners for Fish and Wildlife Program. Section
1.13.I on Service fire management policy recognizes
that prescribed fire is an important and acceptable
tool to remove exotic species and gives guidelines for
using Partners funding for prescribed burning.
7 RM 8 Exotic Species Introduction and
Management
This policy affirms that the NWRS exists for the
protection and management of plants and animals
native to the United States. It outlines the special
circumstances under which the continued existence
of nonnative plants or animals may be permitted.
In particular, it discusses the requirements for
releasing biocontrols onto a refuge.
7 RM 14 Pest Control
Although this policy deals largely with the use of
pesticides on refuges, it does affirm that one of
the objectives of pest management activities on
refuges is to control exotic species and allow normal
populations of native species to exist.
The National Strategy for Management of
Invasive Species
National Wildlife Refuge System (2003)
This document was developed by a Fulfilling the
Promise Team with the support of the regional
refuge chiefs. It outlines a comprehensive strategy
for dealing with the critical problem of invasive
species on National Wildlife Refuges. The plan
was developed in the context of Executive Order
13112 and the National Invasive Species Council
management plan. A copy of this strategy may be
found on-line at: http://www.fws.gov/invasives/pdfs/
NationalStrategyFinalRevised05-04.pdf
U.S. Department of the Interior
U.S. Fish & Wildlife Service
http://www.fws.gov
March 2009